Original subtitles

[suspenseful music]

- Tonight, in the shadow of 9/11,

a new kind of terror strikes at the heart of America.

- This is the first death by Anthrax in the United States

in more than 25 years.

- This silent killer is out there.

You could just simply open up your mailbox,

and that could just kill you.

- Every day, it seems as if more and more people

are getting sick.

- Panic spreads around the country as the poisoned letters

keep coming.

- This can spread very rapidly and it's very dangerous.

You could be looking at thousands of victims.

- Random people seem to be getting sick and dying.

Fear and terror is really at a high.

- The killer has access to military bioweapons labs.

Perhaps something has gone on

that the government doesn't want us to know.

- Now, we investigate the top theories

surrounding the deadly act of bioterrorism

that shocked the nation.

Just who was responsible for the anthrax attacks of 2001?

[dramatic music]

- [Laurence] October 2nd, 2001, just a few weeks

after the 9/11 attacks, 63-year-old Robert Stevens,

a photo editor for the "National Enquirer" tabloid,

stumbles into the ER with flu-like symptoms.

- Robert Stevens is showing symptoms

including high fever, vomiting, and disorientation.

And the hospital admits him with a diagnosis

of bacterial meningitis, which is

swelling of the tissue around the brain.

After he's admitted, within five hours,

he starts having seizures and he slips into a coma.

- Very quickly, multiple organs start failing

inside of his body,

and they recognize that they're in a race against time

to determine what's making this man ill.

When they take a spinal tap

and subject it to microscopic analysis,

they have a a real shock.

They're surprised to discover

that it's not bacterial meningitis.

This man has been infected with anthrax.

- Anthrax disease caused by the bacteria Bacillus anthracis

and it's usually transferred cutaneously,

so through the skin.

Another type of way to get it is through ingestion

or the type of anthrax that Stevens has, inhalation.

And with inhalatial anthrax, about a hundred percent chance

that you're gonna die without treatment.

You don't get symptoms right away.

So it takes a while for those symptoms to show up

and by that time, sometimes people don't even respond

to antibiotics.

Then, your body just starts to really fail very quickly.

- Stevens fails to respond to antibiotics

and the infection continues to ravage his body,

causing sepsis, and ultimately organ failure.

- [Laurence] Stevens dies on October 5th,

four days after checking into the hospital.

The first anthrax fatality in the US in more than 25 years.

- When Stevens dies from his anthrax infection,

basically a panic ensues, because they're not certain

where he could have possibly come into contact with anthrax.

This can spread very rapidly and it's very dangerous.

And if you have a massive outbreak, its self-propagates.

You could be looking at thousands of victims.

- This is 2001, and it's less than a month

after the 9/11 attacks, so people are a bit on edge.

The Center for Disease Control,

even the FBI has gotten involved

'cause anthrax is a very, very scary and virulent condition.

- What's also tricky with anthrax

is that it can take up to seven days

for anybody to exhibit symptoms.

Investigators go everywhere Stevens had been

in the last week, including his offices at American Media,

which owns the "National Enquirer".

- They start doing a pretty intensive search

for the anthrax bacteria.

One place that pops up is on Robert Steven's keyboard.

They also find it in a mail room employee.

He's showing some symptoms.

So, they have those two cases.

And after that, they shut down the AMI offices.

- [Brandy] If you're going into a space that has random spores

of anthrax just in the atmosphere,

that means hazmat suits, that means ventilators,

that means people in big masks in.

It looks like a science fiction movie.

It's very, very scary.

And now, you can't keep this under wraps anymore.

You've got additional people infected.

It's clearly not an isolated event.

- [Laurence] For the authorities,

there's only one logical explanation.

This has to be an act of bioterrorism.

- [Paul] After World War I, there was a recognition

that chemical warfare was unacceptable,

but they did not necessarily extend to biological weapons.

In the post-World War II era, both the United States

and the Soviet Union produce substantial stockpiles

of bioweapons to include weaponized anthrax.

- [Eric] Anthrax, for a long time, has been thought of

as a potentially potent biological weapon.

It's indestructible, and that can be made into forms

that are very hard to detect and very small.

- [Paul] Ostensibly, biological weapons are outlawed

by the Biological Weapons Convention,

but they are allowed to produce stockpiles

for the purpose of research and the production of things

like vaccines, inoculations, and treatments.

- The FBI tries to head off growing panic by insisting

that they're treating this as an isolated case.

But behind the scenes, there's definitely growing concern

that this might be part of a much broader attack.

- [Laurence] On October 12th,

just four days later, the FBI's fears are realized.

An employee from "NBC News" in New York

has also been exposed to anthrax.

- Casey Chamberlain, who works for Tom Brokaw,

opens his mail.

She'd received a letter, and it was very upsetting.

It had a childish hand scrawl,

and it said "Death to America.

Death to Israel.

Allah is great," in it.

And in addition, it seemed to have this strange,

powdery, sandy-like substance in the envelope.

She starts having flu-like symptoms.

It doesn't take long for it to become apparent,

she too has come down with anthrax.

- [Reporter] The news raced across the city's ticker tape.

The mayor tried to reassure the population

this was just an isolated case.

- It is likely that this issue

all began way back on September 25th.

So, one piece of good news

is that if anyone else was gonna be infected,

it would've happened by now.

- [Kavitha] Over the next few days,

seven additional anthrax cases are reported

at news organizations around New York,

including at NBC, ABC, CBS, and the New York Post.

And less than a month after 9/11,

everybody in New York is on edge.

- [Eric] We've been hearing since September 11th,

the enemy of America, who has shown a spectacular ability

to attack America, is Al-Qaeda.

So when a biological attack begins

so soon after September 11th, makes sense

that Al-Qaeda would be the first place you'd look.

[tense music]

- [Laurence] On October 15th,

fears of a coordinated terrorist attack

are seemingly confirmed when anthrax

reaches the heart of the federal government.

- Grant Leslie, an intern for Senator Tom Daschle,

opens up his mail,

and she sees an envelope

that's addressed to Senator Tom Daschle.

The return address is 4th Grade, Greendale School.

So she thinks by the block lettering

that this is a nice letter from some school children.

She opens it up

and a white powder comes out of the envelope.

- The letter that is received is hand scrawled.

It's almost childish in the way it looks

and the message is similar too, but it's longer this time.

- [Matthew] It reads, "9-11-01.

You can't stop us.

We have this anthrax.

You die now.

Are you afraid? Death to America.

Death to Israel. Allah is great."

Investigators come, they quarantine the office

and they find another letter.

This letter was addressed to Senator Patrick Leahy.

That letter also contained anthrax.

So, they close down the Capitol.

They treat all of the staffers there with antibiotics

and they find about another 30 infections

due to inhalation anthrax.

- People are terrified, because they can't see anthrax.

They have no mechanism to

protect themselves against anthrax

and now, you have three discreet attacks

that are very obviously an ongoing campaign

and it's got the public in a panic.

The vast majority of the population

has leapt to the expectation that this is Al-Qaeda

carrying out the next stage in a terror campaign.

- The narrative was already in place

that this was more likely another Al-Qaeda

terrorist attack on the United States

and so, people tried to start putting pieces together.

- [Eric] The ringleader of the 9/11 attacks, Mohamed Atta,

had been in South Florida,

not far from that AMI office,

learning to fly aircraft near an airfield,

where they had a crop duster

and he was asking a lot of questions about the crop duster.

It seems to some people

like there was certainly a lot of smoke there, if not fire.

- [Ali] That, of course, heightens the fear,

because the crop duster with anthrax

could put millions of spores across a large city

and kill millions of people.

- [Laurence] Despite this public concern,

investigators can't find a clear link to Al-Qaeda.

The question is, who else is a suspect?

- So the one unifying factor

between the attacks at the Capitol, the attacks on media

is that these are all being sent through the mail

at a large facility that actually sorts the mail

for the Capitol, two postal workers end up dying.

More people are infected.

Lots of people have been exposed.

- So, the FBI immediately goes to the postal facilities

and starts backtracking where the mail was sent from

and they start checking the cameras.

They do multiple searches across dozens of sites

and nothing to show for it.

And so, the FBI really doesn't have a clue who's behind it.

- By late October, 2001, nearly 20 people

have contracted anthrax infections

and three have died, with hundreds more being treated

for exposure.

Still, investigators have no idea

who's been sending the deadly spores through the mail.

- As this investigation continues to expand,

the United States government sets up an anthrax task force

and they're going to pull in multiple agencies,

all of whom have overlapping responsibilities

to try to bring all of the resources together

to stop these attacks.

- The first wave of letters sent to the news agencies

in New York all have a Trenton, New Jersey postmark address

and were all sent on the same date.

September 18th, 2001.

- The letter to Tom Brokaw has no return address.

It's just addressed to Tom Brokaw, NBC News.

The letter to Tom Daschle does have a return address.

Return address is the Greendale School

in Franklin, New Jersey.

There is no Greendale School in Franklin, New Jersey.

It's a fake return address.

- It becomes apparent that all of these letters

have been photocopied on a photocopy machine,

and then cut to slightly different sizes

before they're sent.

The other commonality between the two sets of letters

is they can't find any fingerprints, no DNA.

Whoever is doing these letters

actually understands how not to get caught.

What's most concerning

has to do with the anthrax spores themselves.

- [Kavitha] The airborne anthrax spores sent to the Senate,

which sickened many and killed two postal workers,

is found to be even more refined and potent

than the spores sent to the news organizations.

- [Paul] As they dig deeper, they determine

that this is weapons-grade anthrax,

which means by definition, it almost certainly

came from a bioweapons lab,

possessed by a major nation state,

but the one we're more focused on is Iraq.

- [Kavitha] Starting around 1985, Saddam Hussein begins

to develop massive biological weapons,

including anthrax.

- During the Iran-Iraq war of the 1980s,

Iraq had deliberately subjected Iranian POWs

to chemical and biological weapons.

- One story is that prisoners of war were tied to beds

inside of a room that was sealed up,

and then they released anthrax into this room.

And through an observation window,

scientists and military personnel

observed their horrific deaths.

- [Paul] After 1991, the Iraqis were expected

by the armistice negotiations

to destroy all of their stockpiles

of biological and chemical weapons,

as well as end any nuclear weapons ambitions.

But the Iraqis played a lot of games.

They tried to hide at least some of their materials

from weapons inspectors.

While the Iraqis publicly claimed

that they had destroyed the stockpiles, privately,

it's clear that they were holding things back.

- [Kavitha] Saddam Hussein has also been threatening revenge

against the US after his defeat in the First Gulf War.

In the immediate aftermath of 9/11,

the US starts to point to Iraq

as a possible partner with Al-Qaeda in the 9/11 attacks

and any ensuing terror attacks against the country.

- [Laurence] When scientists test the anthrax used

on Capitol Hill, some say they uncover the proof

of an Iraqi connection.

- And in late October, we get this bombshell report

from "ABC News," that the anthrax

contained another material called bentonite

and it was made to weaponize anthrax

and make it easier to disperse and more lethal.

The intelligence said that bentonite

was only used for the production of anthrax

by one country in the world,

and that country was Iraq.

- [Laurence] On October 31st,

two days after the news report

tying the anthrax attacks to Iraq,

there's another fatality.

- So far, all of these have been targeted attacks,

the media, the financial institutions,

but then we have a 61-year-old stock clerk in the Bronx

who comes down with anthrax and she dies.

- [Reporter] 61-year-old Kathy Nguyen of the Bronx

died of the inhaled form of anthrax.

So far, officials have not been able to trace

how she got it.

- [Eric] She hasn't been to the offices of NBC News, recently.

She hasn't been to the offices of the "New York Post."

She hasn't been sorting mail.

So, how did she get this?

It raises this possibility that anthrax

is being dispersed in a way that could infect

anybody, anywhere, which is very scary.

- [Matthew] A couple of weeks later,

94-year-old Ottilie Lundgren from Connecticut

also contracts inhalation anthrax and dies.

Now, this is a person that was basically home bound.

She did not leave her home very often.

She did not work for the media,

did not work for the government.

This is another innocent person that has no connection

to be a typical target for this attack, but another death.

Again, just showing how this killer is out there

and that you could just simply open up your mailbox

and that will just kill you.

- [Paul] This is a stark reminder that this is a spore

that has been upgraded

from its naturally occurring, very dangerous state

to make it possible for it to propagate

as widely as possible.

It's essentially an uncontrollable weapon.

Once you release it on the public, it could go anywhere

and this absolutely terrifies people.

And if there's a connection to an external actor,

like Iraq, that might be supporting

the world's largest and deadliest terror organization,

panic is about to ensue.

- [Laurence] Reports then emerge

of a top secret Al-Qaeda and Iraqi intelligence meeting

in Prague, which if true would have explosive consequences.

- [Eric] There's one intelligence report

that the ringleader of the 9/11 attacks, Mohamed Atta,

met with a member of the Iraqi intelligence

in a meeting in Prague.

- [Kavitha] The report backs up a growing suspicion of a link

between Al-Qaeda and Saddam Hussein.

So when the anthrax attacks happen,

it's not a stretch to think that we're in the midst

of another targeted, coordinated attack,

with Al-Qaeda and Iraq working together.

- [Paul] Vice President Dick Cheney publicly confirms

that Mohamed Atta had met with an Iraqi agent

during a national media appearance.

- [Laurence] Despite Cheney's suspicions,

no Iraqi link to Al-Qaeda is ever proven.

Scientists also begin to back off their claim

that there was bentonite, an Iraqi bioweapons signature,

found in any of the anthrax letters.

- [Brandy] Despite the fact that it seems

like these two things are connected,

no link ever really emerges.

There's never proof that Al-Qaeda is working with Iraq

or with Saddam Hussein.

So ultimately, we're back to square one, not really knowing

where the attacks are coming from or who is targeting us.

- [Laurence] In late October, 2001,

the anthrax investigation turns in a new direction.

The FBI reveals that the spores used in the attacks

came from a strain of bacteria

developed in US military labs.

It's known as the Ames strain.

- [Kavitha] The Ames strain was originally isolated

from an infected cow back in the 1980s

and it was taken and used by the military

to try and develop an anthrax vaccine.

- [Laurence] Even after identifying the strain,

investigators are no closer

to finding out who's been sending it.

- There's not really a way to narrow down

exactly where the source must have been,

because it is still distributed into multiple facilities.

And so, the next attack could be around the corner

and you're still not sure

where the original source material was

or how much of it was available to the attacker.

- [David] The strain was kept and used for research purposes

in 15 labs across the United States

and three labs internationally.

So, that was the initial focus

was to try to determine who in those labs

might have had the the means and the motive

to weaponize the spores for the anthrax attacks.

- [Kavitha] Meanwhile, Americans continue to brace

for another possible attack from Osama bin Laden

and Al-Qaeda.

With the public already on edge

about an external terrorism attack,

the FBI is wary of making the public even more jittery

about potential homegrown terrorism,

so they continue their investigation

in complete secrecy.

- [Laurence] As the weeks pass with no news,

frustration grows,

especially within the scientific community.

- [Paul] For the scientists, they're horrified

that something they might have had a hand in producing

is being used to target and kill Americans,

but the FBI seems to be becoming more suspicious

and even adversarial towards them

as they the leadership of the investigation

becomes more convinced

that this was probably a domestic attack.

[suspenseful music]

- [Kavitha] In February, 2002, Barbara Hatch Rosenberg,

who is the chairwoman

of the Federation of American Scientists

and somebody who's been a staunch

anti-bioweapons crusader,

she publishes a blog post called

"Is the FBI 'dragging its feet.'"

And she says that based on her conversations

with scientists, she believes that the attacks

are the result of a military-led bioweapons project

that's gone awry.

She claims that for months, the FBI has known

that the perpetrator of the anthrax attacks

is actually an American.

- [Ali] For the scientists investigating

this outbreak or attack on Americans,

they went from assisting with the investigation

to potentially being suspects of the investigation.

Then, you had no idea that all of this information

that you were being given by these various scientists,

if one of them was the culprit,

you may have gotten inaccurate information.

So, it completely changes the whole dynamic

of the investigation all of a sudden.

- [Brandy] Rosenberg suggests

that the person who has done this,

the person who is behind these attacks

was probably preparing the anthrax in the summer of 2001.

Then 9/11 happens in September

and offers the perfect cover.

That instead of Al-Qaeda being behind this,

the killer is actually blaming Al-Qaeda

to hide their own nefarious activity.

- [Paul] There are certainly some that argue that handwritten

notes with basic grammatical errors

are not the hallmark of an Al-Qaeda communication,

but in the American mindset it played towards a stereotype.

If these attacks were carried out by an American,

that individual was using the anthrax letters

to throw off suspicion.

- [Brandy] Rosenberg isn't alone in feeling

that something is amiss here in the FBI's investigation.

Other scientists claim that for one thing,

a single lone rogue worker wouldn't be able to create

the kind of spores that we see in the attacks.

She also suggests that the FBI

must know that the killer has access

to military bioweapons labs

and in these bioweapons labs,

perhaps something has gone on that the government

doesn't want us to know.

- [Laurence] The assertion is tied

to an international bioweapons ban

that the US signed in 1972.

- [Kavitha] There are suspicions that despite signing this

treaty, the United States never actually dismantled this program

and that they've continued

to develop military grade bioweapons,

including anthrax for years.

- [Paul] If the US was caught in violation

of something like the Biological Weapons Convention,

certainly the US would lose some of its moral authority

in the international sphere.

It would certainly make us look like hypocrites.

- [Brandy] Rosenberg's most shocking claim

is that the government is afraid to arrest

the person involved, because it will show

that the problem is linked to bioweapons labs,

potentially to activity that the government

isn't supposed to be doing

and that they're doing in secret,

and that as a result, they're looking the other way.

- [Paul] There's an enormous amount of political

and public pressure on the FBI to get results.

The public is starting to wonder

if maybe the FBI is the wrong organization

for this type of investigation.

- [Kavitha] The FBI vehemently denies dragging its feet

in order to prevent a national security scandal.

The FBI now turns its investigation

to homegrown terrorists.

They start focusing on suspects with scientific backgrounds

and access to the deadly pathogen

with ties to military infectious disease labs.

- [Laurence] More than nine months

since the anthrax terror attacks began,

there's seemingly little progress in the case

and the FBI is under enormous pressure

to catch the perpetrator.

The FBI interviews hundreds of scientists

working in the field, pulls together their list

of potential suspects, and in June of 2002,

they close in on their man.

- [Brandy] Steven Hatfill has a lot of the credentials.

He is somebody who works in microbiology.

He is a scientist and has connections

to an army research lab on infectious diseases

at Fort Detrick in Maryland

- [Kavitha] Under FBI questioning,

Hatfill denies having any involvement

or knowledge in the anthrax attacks

and even agrees to take a polygraph,

which he reportedly passes.

- [Paul] The FBI knows full well that polygraphs

are not legally admissible and they're not infallible

and so they continue to dig deeper into Hatfill's life.

So that they can go into Hatfill's home

and look for any evidence of any anthrax spores

or anything else that might implicate him in the attacks.

However, the FBI or at least someone within it

tipped off the press as to what they were doing.

An enormous media circus follows.

Hatfill's home is under constant observation by media

and Hatfill himself cannot set foot

outside without being constantly harassed.

- [Brandy] As more information comes out about his background

in bioweapons, the public also becomes convinced

that he's guilty.

This is long before any trial.

He is not even been arrested yet,

but there's this sense that he must be the right guy.

[suspenseful music]

- [Paul] The bureau seems to be developing almost tunnel vision.

They think they found the right person

and they're going to follow it up

until they prove that he's the responsible actor.

- [Laurence] As agents

comb through Hatfill's background,

they uncover even more troubling connections to the case.

- [Eric] There's another weird coincidence

with Stephen Hatfill.

The return addresses to the Tom Daschle

and Patrick Leahy letters were from a place

called the Greendale School in Franklin, New Jersey.

Well, it turns out where Steven Hatfill

went to medical school in Zimbabwe,

there was a town right next to that place called Greendale.

- [Kavitha] In the late '90s, Hatfill gets a job

working for a large defense contractor with ties to the CIA,

but when he applies for a high level security clearance,

he reportedly fails his polygraph test.

This all happened in the summer of 2001,

about a month before the first of the Anthrax letters

is mailed.

- [Brandy] A few years earlier,

Hatfill had been working on a contract about biodefense

and he commissions a study.

And this study was what would we do in the situation

where the US was being attacked by Anthrax through the mail.

He even figures out exactly how much anthrax

would have to be in each letter to be lethal.

- [Laurence] Investigators believe

this could have served as a dry run for the 2001 attacks.

They soon find even more suspicious material.

- On Dr. Hatfill's computer in his home,

when they execute the warrant, they find a novel

that he had written three years before the Anthrax letters

and it's about a rogue scientist

that unleashes a biological attack on Washington, D.C.

- [Paul] Another piece of interesting circumstantial

evidence is that Hatfill had actually been taking Cipro,

the very antibiotic that's used

to treat anthrax infections a couple of weeks prior

to the first launch of the attacks.

- [Laurence] Although the case

against Hatfill seems solid,

he continues to insist he's innocent.

- I am not the anthrax killer.

I know nothing about the anthrax attacks.

I had absolutely nothing to do with this terrible crime.

- [Matthew] Investigators connecting these dots.

He wrote this book.

He wrote the blueprint to the anthrax letter.

He's taking Cipro, the actual drug that you would take

if you came in contact with anthrax.

It's not hard for them to believe that.

I mean, this has gotta be the guy, right?

- [Kavitha] Despite all the circumstantial evidence against

Hatfill, there's still not enough to arrest him,

but that doesn't stop FBI investigators

from continuing to look into him and surveil his home.

- [Brandy] There are people following him everywhere he

goes, following him so closely that in fact,

in one instance, they run over his foot in a car.

Try as they might to connect the dots, they can't.

There just isn't any direct line

between the events of the anthrax attack and Hatfill.

They can't make it stick.

- [Eric] So the investigation against Hatfill

basically goes nowhere.

In 2003, Hatfill sues the federal government,

"The New York Times,"

and he eventually wins the lawsuit against the government

and they settle with him for about $6 million.

By the mid 2000s, this investigation,

they've had 9,000 interviews.

They've had 6,000 subpoenas.

They've done 67 searches,

and they have come up with nothing.

- [Laurence] Five years after the anthrax attack,

the FBI regroups.

The new agent heading the investigation

orders task force members

to review the case files for overlooked leads.

- The FBI never gives up on the investigation

and they are still following up

at the various bioweapons labs.

In particular, they're looking at Fort Detrick,

partially because its geographic location

puts it relatively close

to where the letters have been mailed.

- [David] One of the first things they do

is seize additional samples.

They wind up seizing a flask

of very synthesized, purified anthrax

labeled RMR 1029.

That's happens to be in the sole possession

of Dr. Bruce Ivins.

- [Brandy] Bruce Ivins had been working with the FBI

all throughout the investigation.

He had supplied them with samples.

He trained them to recognize anthrax spores.

At the same time, he too had access

to the kinds of materials that you would need,

access to labs, and for the first time,

the FBI starts to zero in and question his own motivations.

[suspenseful music]

- [David] Bruce Ivins is a senior microbiologist,

who has worked at Fort Detrick for 27 years.

20 of those years working with anthrax.

He is Dr. Anthrax.

- [Kavitha] He's one of the leading anthrax researchers

in the United States and after 9/11,

he's put under enormous pressure

to develop an anthrax vaccine for troops.

Just after the anthrax letters are postmarked,

he sends a letter to a friend

saying that bin Laden definitely has access to anthrax

and that he just decreed death to all Jews and Americans.

- [Paul] Many believe that he's really trying to draw attention

to the potential danger

associated with a widespread biological attack.

- [David] The argument is that he did this

to justify his own continued research.

That there had not been any anthrax attacks prior to this,

and so 9/11 gives him the perfect backdrop

to demonstrate the need for a vaccine

and the continued funding to continue to research

a viable vaccine.

And that according to the FBI is what prompted him

to carry out these attacks.

- [Paul] If Ivins is responsible

for carrying out these anthrax attacks,

he did a pretty good job of covering his tracks.

The FBI doesn't have hard evidence linking him

to the attacks yet and really doesn't have a clue

who's behind it.

- [Laurence] Then a major scientific discovery

leads to a potential break in the case.

- [Brandy] In 2007, breakthroughs in genetic testing

allow them to reanalyze the spores.

And this means they can trace the anthrax

back to its original batch.

- [Paul] They start analyzing

a thousand or more different samples

of the Ames strain from all the different places

that it's held and they discover

that there are unique markers in the specific spores

that were used in the attacks.

They're actually able to backtrack it

to one very specific batch of anthrax

that had been cultured and stockpiled at Fort Detrick.

- [Laurence] For the FBI,

the discovery is a game changer.

What had once been the subject of a global hunt

now sits inside one flask on a lab desk.

- [Kavitha] There are around a hundred scientists

with access to the flask of anthrax that's labeled RMR 1029,

but the FBI turns its attention to the man at the top,

the sole person who has had sole possession of the flask

since the very beginning

and that's none other than Dr. Bruce Ivins.

- [Ali] There was numerous reasons to suspect Dr. Bruce

Ivins besides the fact that the Ames strain was his repository.

For example, right before the time

when the two batches of letters would've gone out,

he had late nights and weekends of work

that were unexplained, which was absolutely atypical

of anything he's ever done in the past.

He also tested his own laboratory

without authorization,

and then sterilized everything without telling people

what he was doing.

There was a lot of suspicious behavior on his part

that he himself couldn't explain

that suggested that he was a likely perpetrator.

- [Paul] When the FBI questioned him

about his changed behavioral patterns,

Ivins claimed that he was having marital troubles at home

and he was essentially throwing himself into his work,

but the FBI wasn't buying that story.

On November 1st, 2007, they executed a search warrant

for Bruce Ivins' home.

When they got inside, they discovered

that there was evidence of a lot of the materials

that would've been associated

with carrying out these types of attacks.

- [Brandy] It's also found out that Ivins

had a history of mental health challenges,

but what's most damning for him is an email he sends

to his friends and colleagues.

In his emails, he seems to be suffering from delusions

and in addition, he states that he's afraid,

he will not be able to control his own behavior.

- [Laurence] But Ivins

continues to stay a step ahead of the FBI

until he's tripped up by an old act of deception.

- [Brandy] In the original investigation,

the FBI asked for samples from all of the different labs

that had military grade anthrax.

And the sample that Bruce Ivins had sent in

had been declared clear

from the strain they were looking for.

Around the same time, Bruce had sent core samples

to colleagues for safekeeping.

Now upon going back, the FBI would discover

these samples did test positive

for the strains that were used in the attacks.

- [David] The FBI contended that he had submitted false samples.

So in July of 2008, he's informed by the FBI

that he is about to be indicted

by a federal grand jury on multiple counts of murder.

He goes home.

He takes a fatal dose of acetaminophen with codeine

and three days later, dies.

- [Laurence] After seven years

with more than 600 investigators on the job

at a cost of nearly $100 million,

the FBI believes the case is finally solved.

- [Paul] On August 6th, 2008 in the aftermath of Ivins' suicide,

the Department of Justice announces

that they hold him singularly responsible

for the anthrax terror attacks of 2001.

As far as the Department of Justice

and the FBI are concerned, the case has been closed

and because Ivins is dead,

there's no further requirement for action.

- [Laurence] Despite the government's insistence

many remain unconvinced.

- [David] There are some critics of the investigation,

including some scientists who contend

that if the FBI fingered the wrong man in Steven Hatfill,

they also fingered the wrong man in Bruce Ivins.

That Ivins was incapable of carrying out these crimes.

It does leave open the door

in the minds of some people anyway

that the real killer may never have been brought to justice.

- [Laurence] Despite the FBI's certainty

that Bruce Ivins is guilty of the anthrax attacks,

many believe the case remains unsolved.

- The FBI is convinced and they close the investigation.

But in the months and years that follow, more gaps and holes

and questions remain.

One of the problems is exactly how you get the anthrax

to the very refined spores

that were sent in the anthrax attack letters.

Other scientists believe

that he didn't have the equipment necessary

to actually make that process happen,

at least not in the quantities

and certainly not in the refinement

that we see in the spores that were used in the attacks.

- [Paul] According to the former deputy director at Fort Detrick,

the spores that were used in the anthrax attacks

were actually substantially smaller

than anything that had ever been produced

in a US or Russian bioweapons program.

- What's even stranger is the FBI

was never able to find any trace of spores on the equipment

Ivins was accused of using to develop the bioweapon.

- [Brandy] Really, the most incriminating piece of evidence

the FBI was able to use against Ivins

was that he was in the vicinity of the flask

and that he had access to it,

but of course we already knew that other people had access.

- There will always be debate

about the efficacy of the science

that was associated with this investigation

and it does leave the door open

as to whether the real killer was ever caught.

[suspenseful music]

- [Matthew] There is no direct physical evidence

to convict Bruce Ivins in this case.

Everything is circumstantial

and traditional forensics on this

come up with a big fat zero.

So no fingerprints, no DNA.

They do handwriting analysis of the envelopes

to known exemplars from his own writing

and they're not a match there.

There's no conclusive evidence

saying that he wrote these letters.

- [Paul] Handwriting analysis is not perfect

and so for the FBI, it's not really a surprise

that the handwriting on the letters

that accompanied the anthrax attacks

could never be perfectly tied to Bruce Ivins.

But for people looking to poke holes in the case,

that's yet another example

of this not being the perfect investigation.

- [Brandy] Of course, the FBI was under enormous pressure.

A lot of time had gone by,

and there was a real desire to close the case.

That might mean pressure

to sweep inconsistencies under the rug.

- [Matthew] Friends and colleagues to Dr. Ivins

state that it's the pressure from the FBI

that caused him to commit suicide,

not the guilt of committing this act.

And in just like Dr. Steven Hatfill,

many believe that if this went to court,

Dr. Ivins also would be exonerated of this.

- [Laurence] Through the years,

several notable organizations

have also challenged the FBI's conclusions.

- [Kavitha] In 2011, the National Academy of Sciences

determines that the scientific evidence alone

was not enough to link the flask from Ivins' lab

to the anthrax used in the attacks.

- [Paul] The FBI's entire physical case around Bruce Ivins

revolves around the idea

that a single flask of anthrax spores was the murder weapon.

If for some reason that was an error,

then the entire case falls apart.

- [Brandy] In 2014, a government body that was nonpartisan

also releases its report saying that the actual science

performed by the FBI was insufficient

and in fact, that genetic signature

might not have been that unique.

- [Kavitha] Perhaps most suspicious of all,

there's no way to go back into the evidence

with new eyes and new technology,

because the FBI destroyed everything,

including the spores,

when they officially closed the case back in 2010.

- [Eric] This is an investigation that's covered so

much ground.

It's been one of the most expensive investigations

in the history of the FBI.

They've interviewed 10,000 people.

They've issued 6,000 grand jury subpoenas.

And at the end, it has this conclusion

that to most people isn't very satisfying.

It's not just that there's some questions.

There are a lot of questions.

- [Paul] The constant speculation

and second guessing of the FBI investigation

definitely provides no comfort to the victim's families.

The idea that someone might have died

just for opening their mail is a terrifying concept

and we want to believe that our law enforcement agencies

are capable of solving this type of case.

And so to have somebody constantly questioning it

on the basis of a belief

that the FBI is not good at their job

can be very frustrating to a lot of those victims' families.

- [Brandy] For many people, there's a great desire

to accept the FBI's conclusions.

For one thing, it means that they got their man

and we can stop worrying about any future attacks.

It's comforting, but it might not be the truth.

And if you don't accept those conclusions,

it means that it's possible that the anthrax killer

is still at large.

[suspenseful music]

- We may never definitively know if Bruce Ivins

was the man responsible for making weaponized anthrax

and sending the lethal letters.

His case was never brought to trial.

And while some have called on the FBI

to reopen the investigation, for now it remains closed,

leaving one of the deadliest bio-terrorism events

on US soil forever cloaked in mystery.

I'm Laurence Fishburne.

Thank you for watching "History's Greatest Mysteries."