Original subtitles

Tonight, a series of shocking murders

terrorizes the city of Boston.

Each victim is found strangled to death in their home

with a telltale bow around their neck.

All of these victims are women.

They live alone.

Almost immediately, the suspect in this case

was named the Boston Strangler.

Law enforcement is under enormous pressure

to find and stop this predator.

This is one of the biggest manhunts in history.

13 victims over nearly two years,

he seems to be killing for sport.

It almost seems like the Boston Strangler

is taunting law enforcement and the people of Boston.

Now, we uncover the top theories

surrounding one of history's most notorious serial killers.

They're looking at the usual suspects of mental patients,

people arrested for sex offenses.

The Boston police have made zero headway in this case.

Boston goes from being scared to being angry.

Ultimately, the Strangler is still out there,

potentially ready to terrorize and murder more women.

Who is the Boston Strangler?

On a June evening in 1962,

in Boston's Back Bay neighborhood,

a young man named Juris Slesers

shows up at his mother's apartment.

Anna Slesers is a 55-year-old divorcee.

On this Sunday, as usual,

her son swings by to pick her up for church.

But he stays at the door for 45 minutes,

knocking and waiting, and she doesn't come out.

She's someone who rarely misses church.

She is also someone though that does suffer

from bouts of depression,

so Juris decides to finally knock the door down

to go inside.

Inside the house, Juris is met with a sight

that no child ever wants to see of their parent.

His mom is lying there

on the floor by the bathroom

with the belt of her bathrobe wrapped around her neck.

She's ice cold.

He calls the cops and he says, "My mother hanged herself."

He assumed that she had committed suicide

because she'd been struggling with depression,

but police immediately felt like something was off.

There are fresh baked muffins on the table.

There's a kettle on the stove.

This does not look like the scene of a suicide.

Something else is going on.

Anna has been sexually assaulted,

and the cord from the robe tied around her neck

is tied in a bow.

This is not the work of a suicide.

This is a murder.

The crime scene yields no evidence.

There are no fingerprints

and the neighbors didn't see or hear anything suspicious.

More than two weeks go by

without any advances in the case,

but the killer is just getting started.

Boston is sweltering.

Retired psychotherapist Nina Nichols

needs to escape the heat from her apartment,

so she decides to spend the afternoon shopping.

She comes back to her apartment at 5:00 PM

and she starts getting ready to go to dinner

at her sister's house.

By 7:30 PM, Nina still has not shown up

to her sister's home for dinner.

The sister begins wondering, and goes to the apartment,

and starts knocking on the door but gets no answer.

So she gets a janitor from the building

to open up the apartment with a master key.

The janitor is shocked at what he finds.

Nina's in her bedroom, half on/half off the bed,

with a nylon stocking wrapped around her neck.

Her apartment has been ransacked,

but nothing valuable seems to have been taken.

Nina Nichols' cash is still there.

It doesn't look like this is a matter of a robbery

and there's no sign of forced entry.

So either it's somebody that the victim knew

or someone who talked her into letting him in.

Detectives note the similarities

between this strangulation killing

and the murder of Anna Slesers.

That same day, 15 miles north of Boston,

in the quiet suburb of Lynn,

yet another older woman is brutally killed.

Police are called to the crime scene of Helen Blake,

a divorcee who's also been strangled.

She too was found with a nylon

tightly wrapped around her neck and tied in a bow.

They also discovered

that the apartment door wasn't damaged, again indicating

that there had been access to the apartment without force.

Three murders, two in one day,

same MO for all of 'em.

Once you have a pattern like this,

there's going to be an immense amount of pressure

on the Boston Police Department.

There's kind of a hysteria that's building up about this.

Media even goes one step further

by dubbing the killer the Boston Strangler.

The police are at a total loss.

They have no sign of connection between any of these victims.

This is random crime that can happen at any time.

Now the public was concerned

that they had a serial killer on their hands

and Boston police weren't moving fast enough

to figure out who this man was.

Boston Police Commissioner Edmund McNamara

is a veteran officer, but he's new in the top job.

McNamara has to take drastic action.

The city is in a panic.

On July 2nd, he takes the extraordinary action

of assigning every single detective

on the Boston Police Department

to the Boston Strangler case.

Thousands of women are taking up judo

and YWCA branches throughout the city

are increasing their classes to deal with the new demand.

People all over Boston start taking steps

to protect themselves.

More dogs are adopted at that time for added protection.

The sale of deadbolts and extra locks on the doors

go up significantly.

People are afraid.

The Boston Police Department established a hotline

where people could call and offer tips and leads.

And in addition to that, they offered a $5,000 reward

to anyone that could give information

that might lead to the capture of this Boston Strangler.

But the hotline doesn't yield

any promising leads.

July goes by without any additional murders.

Then in August, a pair of grisly discoveries

reminds the people of Boston

that the Strangler is still among them.

The fourth victim,

a 75-year-old woman named Ida Irga,

is also discovered dead.

She's lying on the floor, still in her pajamas,

with a pillowcase wrapped around her neck.

The next victim is a 67-year-old nurse named Jane Sullivan.

She's found in her bathtub with her head underwater.

Jane Sullivan not only had been strangled,

but it took about a week for them to discover her body.

Now that the death toll has reached five,

fear is turning to anger.

These are all older ladies living alone

who have been killed by some fiend,

and the people of Boston wanna know,

why haven't the Boston Police Department found anyone?

It is not until the end of 1962

that police finally focus on their first viable suspect.

The police will spend the next six months

rounding up any known sex offenders in the area.

One of those is a man by the name of Arnold Wallace,

who's caught breaking into a tea shop

in the Back Bay neighborhood in Boston.

Arnold Wallace is not the real name

of this 26-year-old mental patient

who had recently escaped

from Bridgewater State Hospital for the Criminally Insane.

He has escaped five times in the last six months, and

all of the murders have taken place

during times when he was out of the hospital.

Records show that he once

physically assaulted his mother

and he obsessively talks about sex.

He readily confesses

that he finds older women extremely attractive,

and one of his favorite pastimes is hugging them.

The more Wallace talks, the more that leads investigators

to think that he might be the Boston Strangler.

Not everyone thinks it's as simple as that.

For one thing, he's clearly not all there mentally.

He seems more goofy than menacing.

Is he the kind of person

that someone's gonna open their door and let in?

Is he the kind of criminal mastermind

who's going to be able to not leave any clues behind

at any of the places where these murders have taken place?

It seems kind of unlikely.

Many at City Hall

push Commissioner McNamara to arrest Wallace

for the Strangler killings,

but before he does, a call comes in

from Boston's Roxbury neighborhood.

There's a 20-year-old student

at the Carnegie Institute of Medical Technology

named Sophie Clark, who is also found dead by strangulation.

There are nylons that are used

to strangle her around her neck, and then they're tied

into that distinctive bow that's become

sort of the trademark of the Boston Strangler.

However, while the other victims are older white women,

Sophie Clark is a 20-year-old and she's Black.

So investigators are confused.

She doesn't fit the bill, and these kind of serial killers

rarely deviate from their particular ideal kind of victim.

The idea that a serial killer

is going to go after five victims

in their 50s or older,

and then suddenly switch to a 20-year-old,

it seems unlikely.

But at this point, the police are kind of desperate

over the Boston Strangler.

December 1962, police believe they finally have

the Boston Strangler under lock and key,

a mental patient known by the pseudonym Arnold Wallace.

But while Wallace is in custody,

there's yet another killing.

Patricia Bissette is a 23-year-old secretary

who was gonna get a ride to work from her boss.

Her boss shows up, doesn't get an answer at the door.

Bissette's boss goes back to work.

But when Bissette doesn't show up at the office,

he returns to her apartment.

He contacts the janitor,

asking for a stepladder to climb into the window.

He crawls into her apartment window

and discovers her sprawled out on her bed,

but the covers are pulled up to her neck.

And when the covers are pulled down,

she has been strangled with four pieces of clothing.

You now have seven women

who have been murdered in less than a year,

and still, investigators do not have

any real leads in this case.

The residents of Boston are no longer sure

if there's just one Boston Strangler out there

or if there's a copycat killer

that's not just targeting older women

but younger ones as well.

In an effort to calm the city,

Chief McNamara promises to explore

every possible tip or lead.

But that promise is tested

when a man named Paul Gordon calls the hotline.

Paul Gordon is a local copywriter/clairvoyant/psychic.

He comes to the police saying he's got important evidence

that he knows who committed these crimes.

He says that he has these visions of the killing

and what the killer looks like.

They bring him into the station,

and other officers recognize him

because he's come into the station before

saying he has information about various other cases.

They never took him seriously.

But right now, they're taking him very seriously

because he starts describing the killer

as somebody with bony knuckles,

and he has this one curl that comes down his forehead.

And they're shocked

because this matches Arnold Wallace's description.

He is describing Arnold Wallace to a T.

So they show him some photographs

and he picks Wallace out of the photographs.

Gordon is taken to Bridgewater State Hospital

to ID Wallace.

And not only does he say, "Well, that's the guy there,"

but Arnold Wallace IDs him.

He says, "Hey, how you doing, buddy?"

They met before, which is crazy.

Detectives learn that Paul Gordon

has actually gone to the hospital

to visit Arnold Wallace in March,

long before Gordon got involved in this case.

Some in the department begin to suspect

that Gordon's trying to pin the murders

on this innocent, mentally challenged man

because he's the murderer.

As the police continue to question Gordon,

their suspicion grows.

He just knows so many details about these murders.

He starts giving descriptions of entryways, and doorways,

and furnishings, and colors of fixtures.

Some of these things haven't been reported on.

Some of these things haven't even been marked down

in police reports.

There's a growing belief

that Gordon's psychic visions

are actually the confessions of a killer

begging to be caught.

When investigators looked into Gordon's background,

they don't find anything suspicious,

except for the times that he's come to the police station

in an attempt to try to aid police officers

who are working on cases.

That doesn't mean Gordon's innocent.

Police are eager to learn if he knows more details

that might give him away as the Strangler.

Police decided that they were gonna interrogate Gordon

under a use of a drug

that they were using back in those days

called sodium pentothal, or the truth serum.

For six and a half hours, investigators questioned Gordon.

All the while, psychologists are watching Gordon

to determine if he's actually telling the truth or not.

Gordon stands by his story the entire time.

He says that he has nothing to do with the murders at all.

Psychiatrists believe that Gordon is telling the truth,

that he's not the Boston Strangler.

Gordon has no real history of violence.

He doesn't really seem to be the perpetrator.

Maybe he really believes he's a psychic,

but in the end, the police decide

that he doesn't seem to be the Boston Strangler.

It's been six months since the first murder.

Every single lead, every single suspect that the police get

are dead ends.

They're no closer to solving this

than they were after the first murder.

No woman is safe in the city of Boston.

Everyone is furious and terrified at the same time.

By the spring of 1963,

there have been seven victims in the Boston Strangler case.

On May 6th,

a discovery just a few blocks from Harvard Square

raises the death toll to eight

when a 23-year-old graduate student is found dead

in her apartment.

Beverly Samans is another victim of the Boston Strangler,

also sexually assaulted, but she's one of the few

that is a victim of violence beyond strangulation.

She's stabbed 22 times.

Four days later in New York City,

200 miles from the Boston Strangler's home turf,

a wealthy divorcee meets a violent end

in a Times Square hotel.

A woman in her 60s, Zenoria Clegg,

who's described as very frail and thin,

who wears a scarf around her neck to hide cancer scars,

is seen at a hotel bar hanging out with a guy

who's super tall and about half her age.

Because they're such an odd couple, everyone notices them.

This unlikely duo spends the afternoon

getting drunk at the bar and then they go up to her room.

Her body is discovered in the room two days later.

She's been beaten, she's been sexually assaulted,

and she's had a scarf tied around her neck,

and she's been strangled to death.

The officer who arrives to investigate

is New York Police Department Detective Thomas Cavanagh.

Smooth talking and intelligent,

Cavanagh is the inspiration for the TV detective "Kojak."

Cavanagh, as he's going through the evidence,

immediately concludes this is really, really similar

to the modus operandi of the Boston Strangler.

Cavanagh questions witnesses

who saw the odd couple at the hotel bar.

It turns out that the man

that was with Zenoria Clegg that night

was actually a regular at that bar in the hotel.

He's a 34-year-old New York native

by the name of Charles Edward Terry.

Seven days after the murder,

Terry is tracked to a bar in Greenwich Village,

and Cavanagh has him taken in for questioning.

Terry almost immediately confesses

to the murder of Zenoria Clegg.

He met Clegg at the bar.

They went upstairs for a sexual encounter.

He said that Clegg then humiliated him,

and in a rage, he strangles her with her own scarf.

It turns out Terry

has his own share of run-ins with the law.

He was in prison for rape in Maine.

And in December 1962, police look at him

as a possible suspect in the strangling of a stewardess

in New Orleans, Louisiana.

So Detective Cavanagh

contacts the Boston Police Department, and he's like,

"Hey, we got a guy here for strangling murder.

We think he could be the guy that you're looking for."

Detectives come down to New York, they talk to him,

and they do kind of a half-ass job.

Terry denies he was ever in Boston

and the Boston police reject him as a suspect.

Critics contend they feared being shown up by Cavanagh.

It would look kind of bad for the Boston Police Department

if this case that they've been working on for months now

is immediately cracked open

by some slick New York police detective.

Charles Edward Terry is arrested

for the killing of Zenoria Clegg.

But just 'cause the Boston police

don't wanna pursue him

doesn't mean he's not the Boston Strangler.

Cavanagh is not gonna let this slide so easily.

Cavanagh assembles a crew of veteran detectives

who go to Boston and conduct their own investigation.

They find out that at one point in time,

Terry stayed at two rooming houses in Boston,

very nearby two of the stranglings.

They start talking to witnesses,

until the Boston PD gets wind of what Cavanagh's up to,

and they tell him to go back to New York City.

Cavanagh considers going to the press

and badmouthing the Boston Police Department.

But while Terry is awaiting sentencing in prison

for the Times Square killing,

the Boston Strangler strikes again.

September 8th, 1963,

it's a Sunday morning in Salem, Massachusetts.

58-year-old Evelyn Corbin has just come home from church,

with plans to join her neighbor

down the hallway for breakfast.

Evelyn Corbin never shows up

to her friend's apartment for breakfast,

so the friend goes down, uses a spare key to open the door.

And Evelyn is found lying on her back, face up,

with two stockings tied around her neck.

This is well over a year since the first murder.

The public is outraged.

Boston residents once again are on edge

because the Strangler is still out there.

November 1963, it's been a year and a half

since the Boston Strangler first struck.

Nine women have been savagely murdered in their homes,

and investigators are still at a loss.

Police don't know how the Strangler

gets into his victim's homes.

They don't know if there are copycat killers at work.

All they know is that they're being outsmarted.

Boston PD still has no solutions.

They go ahead and they double the reward money.

It's $10,000 now per victim,

$1 million in today's dollar value.

It's a huge sum of money.

And with huge sums of money

come huge, unintended consequences.

The plan to double the reward backfires on the Boston PD.

They were bombarded with all this information,

people calling into the police station

alleging friends, and neighbors, and family,

ex-wives implicating their ex-husbands.

It just bogged down the investigation

and just further confused

who is really a viable suspect here.

The hotline and the increased reward money

get a lot of media attention,

but do nothing to stop the killer from striking again.

In late November 1963, 23-year-old designer

and Sunday school teacher Joann Graff

is found strangled to death in her home

just 30 miles north of Boston.

A little more than a month later,

the Strangler kills again in the heart of the city.

Mary Sullivan, 19-year-old,

her first day living in Boston.

She doesn't make it to day two.

She's found the day after she moved in strangled to death.

Like all the others,

the same signature knot, the Strangler's knot,

is around her neck, fashioned into a bow.

In between Mary Sullivan's toes is a New Year's card,

as if the murderer is being cheeky

with the police department,

like, "You can't catch me. Happy New Year."

Two weeks after Mary Sullivan's murder,

Massachusetts Attorney General Edward Brooke

takes over the case

from Boston's floundering police chief.

Now we have the attorney general inserting himself

from a state level into a city jurisdiction

to bring this situation to a close.

He's an African-American attorney general

in a mostly Caucasian environment, that being Boston.

But the bigger conversation was not just the AG coming in,

but who he brought in with him.

Brooke assigns the case

to his good friend from law school,

Assistant US Attorney John Bottomly.

Bottomly's first act is to collect all pieces of evidence,

every police report, and he starts to collate them

into a new machine.

He's bringing computer science into policing

for maybe the first time ever.

This allows everyone working on

the Strangler case to share all the available

information and evidence.

While Bottomly's doing that,

Brooke sets about assembling a task force.

It's experts in psychiatry, in forensics, in police work,

and it's people from outside of Boston.

And you can imagine how the Boston Police Department

might have felt about that.

This is very unpopular among the police.

To them, it really looks like a slap in the face.

While we have this fight going on

between the special task force and the Boston PD,

a smaller task force is looking into a rash of rapes

in the Boston area in which the victims are not killed.

Victims report that a man came to their door

dressed in green work clothes,

claiming to be a handyman sent by the landlord.

In the most recent attack, a woman lets in a man

who says he's there to fix a leaky pipe.

He sexually assaults the woman and then flees.

A few days later, this same man apparently

knocks on the door of this apartment,

but the woman refuses to let him in.

He eventually storms off,

but over the course of this,

he is seen by about a half dozen different witnesses.

The man is quickly identified

as 33-year-old Albert DeSalvo.

Police arrest him

and take him to the station for questioning.

He's first sent to Bridgewater State Hospital

for a psychiatric evaluation.

The more the police look into him,

the more it looks like he could be the killer.

Mr. DeSalvo was found to have

a very, very long rap sheet,

hundreds of crimes from a very young age

that all centered on sexual deviancy.

He was viciously assaulted by his father multiple times.

He claims he saw his father break his mother's fingers.

He claims his father would

frequently bring home prostitutes

and have sex with them in front of him.

This is a traumatized man.

And to the psychiatrist, to the investigators,

this could be a person who could mature

into a serial killer.

In some ways, DeSalvo feels like a perfect fit

to be the Boston Strangler,

but what they can't figure out is why a serial killer

would all of a sudden start leaving his victims alive.

Bottomly conducts a series of interviews

with DeSalvo, who admits to hundreds of break-ins

and sexual assaults, but denies killing anyone.

Nothing that he says and nothing that the detectives find

actually links him conclusively

to the Boston Strangler's crimes.

But curiously, while he's in custody,

no other women are strangled.

In March of 1966,

Bottomly gets a surprise phone call from a lawyer

claiming to represent Albert DeSalvo.

The man on the other end of the line is F. Lee Bailey,

who gains notoriety from defending a man

by the name of Sam Sheppard,

who was wrongfully accused of murdering his wife.

The Sam Sheppard case was very famous.

It inspired a TV series in 1963 called "The Fugitive"

and a movie version of it that came out in the 1990s.

Bailey tells Bottomly that his client

is prepared to confess to the Boston Strangler murders.

DeSalvo is willing to do this on one condition,

that none of these confessions can be admitted to trial.

DeSalvo is not going to be convicted

for any of the Boston stranglings.

While Bailey never overtly explains

why DeSalvo would confess to being the Boston Strangler,

Massachusetts at this time

does not have a death penalty for sexual assault

but does have a death penalty for murder.

Prosecutors conclude they have

more than enough evidence

to send Albert DeSalvo to prison for life,

so they end up taking the agreement.

I think there's a lot of people

that are gonna sleep better tonight, especially women.

The prosecutors know that they can close those cases

and they could announce to the public,

"We took a bad man off the streets for life."

In the summer of 1966,

DeSalvo confesses not only

to the 11 known Boston Strangler murders,

but also two more unsolved killings

not previously linked to the Strangler;

that of 80-year-old Mary Mullen in June of 1962

and 69-year-old Mary Brown in March of '63.

In all, DeSalvo confesses to murdering 13 women.

Bottomly officially announces to the press

that the Boston Strangler has finally been caught

and the city itself celebrates.

The long nightmare is finally over.

DeSalvo's confession

makes Bottomly a hero,

but some come to doubt the authenticity of that confession.

Later researchers obtain copies

of Bottomly's interrogations,

and they find he's not the most seasoned interrogator.

There are parts of the interview,

it seems like Bottomly is showing him

photographs of the crime scene.

It's done with a bunch of leading questions.

When DeSalvo gets answers wrong,

he's asked a question over again to change his answer.

Relatively quickly, there are some people who doubt

that DeSalvo is the guy.

Ames Robey, a doctor who worked with DeSalvo

at Bridgewater State Hospital, just has his doubts.

He doesn't think DeSalvo fits the profile.

He thinks that DeSalvo just desperately wanted

to be someone famous, someone remembered.

After nearly five years and 13 murders,

authorities believe they finally have the Boston Strangler

behind bars.

The fact that Albert DeSalvo was arrested

for a separate series of assaults doesn't matter.

As long as he's off the street,

that's good enough for Boston's police force

and its citizens.

There were two women who say they actually saw

the face of the Boston Strangler.

Those women were brought into the police headquarters

to take part in a lineup of potential suspects.

In that group of suspects was DeSalvo.

One of 'em, Marcella Lulka,

was a neighbor of victim number six, Sophie Clark.

Marcella claims that she had an encounter

with a man on the same day that Sophie Clark is found dead.

Marcella Lulka said that that day,

someone knocked at her door.

She went and answered it.

And he says,

"The super sent me here to paint the apartment."

Marcella doesn't have a good feeling about this guy,

and she's like, "You can't come in now.

My husband is asleep in the other room."

And he flees the scene.

The other woman who joins to look at the lineup

is a woman named Gertrude Gruen,

who says that a man broke into her house

and attempted to attack her,

but she fought him off and he ran away.

Interestingly, the women failed to pick DeSalvo

out of the group of men,

but they did both independently point at one person

as the Boston Strangler, and that person was George Nassar.

When the police dig into Nassar's past,

they find a checkered history of violent crimes.

George Nassar is a career criminal,

starting with his first murder at the age of 15.

He went to do a robbery at a store

and he shot the store clerk four times in the chest.

He then is sentenced to 20 years in prison

and he's let out for good behavior after 13.

In 1964, he goes to a gas station,

he puts the gas station attendant to his knees,

and shoots him execution style.

Then he realizes that there's two witnesses;

a young mother and her teenage daughter

were at the gas pumps.

He then goes toward them,

he fires a couple of shots at their car,

then runs out of bullets.

And he ends up taking off in his own car.

The testimony of the mother and daughter

puts Nassar behind bars.

And to add to the mystery,

police, when they look into Nassar's background,

find out that he actually was free and on the streets,

out of prison, during the time of the Boston stranglings,

which made him again a really interesting suspect.

After Marcella Lulka and Gertrude Gruen

identified Nassar as their assailant,

he's questioned about the Boston Strangler killings.

He was very clear that he knew nothing

about the Boston stranglings.

It was only until later,

when he was speaking with Dr. Robey,

that he revealed the fact

that he had heard about the Boston stranglings

from Albert DeSalvo.

Dr. Ames Robey knew both Nassar

and DeSalvo from their time

at Bridgewater Hospital for the Criminally Insane.

Initially, when DeSalvo is a suspect,

Dr. Robey, he didn't agree.

He's like, "He's not a murderer. He doesn't have it in him."

But he did think that Nassar could be the Boston Strangler.

He noticed that on several occasions,

that Nassar and DeSalvo were talking,

in hushed tones, by themselves.

It seemed like Nassar was coaching him

to say certain things in a certain way,

giving him information.

Robey believes, along with others,

that Nassar shared intimate details of the Strangler crimes

so that DeSalvo would claim that he did it,

looking for glory and fame in being the Boston Strangler.

The theory goes that Nassar

would turn DeSalvo in for the reward

and split it with DeSalvo to give to his wife and children.

The two incorrectly assume

that they are eligible for that reward money,

but because they're convicted felons, they are not.

But there are other ways

to make money off these notorious crimes.

DeSalvo also knew that there'd be books

and movies written about this,

and that he wanted a cut of it.

It's Nassar who connected DeSalvo

to his defense attorney, F. Lee Bailey.

Up until Bailey came on the scene,

DeSalvo had been vehemently denying

that he had anything to do

with the Boston Strangler murders.

Then all of a sudden,

Nassar connects him with this new lawyer

and suddenly he's claiming that he committed all of them?

It just seems a little odd.

When confronted, Nassar denies any involvement

with the Boston Strangler crimes.

He says, "All the information I have

came from my distraught fellow inmate, DeSalvo,

who gave me all the gory details."

Nassar is hoping for a retrial of his murder conviction.

He knows he's not gonna get that

if he confesses to more murders.

Police finally decide that the case against DeSalvo

is much stronger than the case against Nassar,

and they kind of let it go.

Both of them are locked up.

Neither one of them

are gonna see the light of day again in Boston,

and the crime stopped.

In 1967, Albert DeSalvo is two years

into a life sentence for sexual assault.

And even though police can't pin the murders on DeSalvo,

the Boston Strangler's killing spree appears to be over.

But not for long.

In July 1967,

a 19-year-old Eastern Michigan University student

is found strangled to death in her apartment.

She was sexually assaulted

and she was strangled with her own clothing.

This bears striking resemblance

to the Boston Strangler murders.

Over the next two years,

six more young women are raped and murdered

in and around Ypsilanti, Michigan.

All but one have clothing tied around their necks.

Dr. Ames Robey, who was in charge

of Bridgewater State Mental Institute in Massachusetts,

where does he live now?

He lives in Ypsilanti, Michigan,

and he's the chief forensic psychiatrist

for Ypsilanti State Hospital.

He is disturbed and unsettled

at how closely these murders

mimic the Boston Strangler murders.

There are fears that the Boston Strangler

may have moved to Michigan to resume his serial killing.

One day, Dr. Robey sees an article

about a student protest.

And in that article is a photograph

of these students protesting,

and he recognizes somebody.

Robey recognizes a man

known by his pseudonym, David Parker,

one of his former mental patients

at Bridgewater State Hospital.

Dr. Robey, he's like, "This is one of the people

that I actually thought was the Boston Strangler."

He starts to think, now Parker's in Michigan,

he's been a student at the university

for the last couple of years.

Could he not only have been responsible

for the Boston Strangler murders,

but also these Michigan murders?

Parker planned to build

and detonate a bomb in Boston in 1961,

and his erratic behavior sends him to Bridgewater,

where he's put under the care of Dr. Robey.

He's then arrested

for beating his pregnant wife in Harvard Square.

She says she feared for her life.

He was beating her regularly

that at one time, after strangling her,

he stops and says, "I choose to let you live."

Parker also expresses a deep hatred

and a deep distrust of women.

And for a while, because of that,

Robey believed that Parker

could have been the Boston Strangler

up until DeSalvo's arrest.

But now, Dr. Robey realizes that once again,

Parker is in the same vicinity

where there are now a string of strangulations.

Dr. Robey calls investigators

and tells them that Parker is here in Michigan

and he fears he may be the Boston Strangler

and is killing again.

Police interview Parker,

who denies any role in the killings.

He's dismissed as a suspect.

But the cops soon get a promising new lead in the case.

An eyewitness comes forward

to say that she saw one of the victims

getting on a motorcycle that a man was driving,

a blue motorcycle.

A police officer who's on campus

notices a young man fitting that description.

He actually knows this person.

John Collins was in his fraternity,

and he was thrown out of the fraternity for theft.

This officer sees Collins

sitting on the back of his motorcycle,

trying to talk to young, pretty girls

walking through campus.

And that's how he's brought in as a suspect.

They start interviewing people in his past

and they see he's got a history of sexual violence.

Past girlfriend said that he was abusive,

that he would choke them, strangle them.

He was not a nice person at all.

Police consider Collins

a prime suspect in these terrifying serial killings,

though there's only enough evidence to convict him

for the last of the seven Michigan murders.

Some researchers find it hard to believe

that Collins is responsible for all seven murders

that take place in Michigan.

It has been suggested that perhaps

he might have had an accomplice.

And that accomplice is David Parker.

Though the Michigan murders

may have nothing to do with the Boston killings,

they keep alive the theory

that Albert DeSalvo may be innocent after all.

In 1973, DeSalvo puts in a call to Robey.

He says, "I'm not the Boston Strangler

and I'm ready to reveal to you exactly who is.

Come meet me in prison."

He wants to speak to him face to face.

Robey says he'll be there as soon as possible.

And that night, DeSalvo is stabbed in his cell.

He's murdered.

The prison officials say it was a drug deal gone wrong,

but Robey's not so sure.

Was he silenced for what he was about to say

about the Strangler murders?

In 2013, investigators employ

new technology in order to solve the murder

of the Boston Strangler's last victim, Mary Sullivan.

The police department reanalyzes

the evidence that they have from Mary Sullivan.

They have semen samples from her crime scene.

DeSalvo is exhumed.

They get DNA from his bones and from his teeth,

and now they have a definitive match.

His semen is on Mary Sullivan.

He is the killer of Mary Sullivan.

For many, this is conclusive evidence

that Albert DeSalvo was the Boston Strangler,

but can we really tie him to all of those murders?

Many others believe that this isn't a case

that should be closed.

In fact, it should continue to remain wide open.

To this day, there's no hard evidence connecting DeSalvo

to the other 12 Boston Strangler murders,

all of which remain officially unsolved.

Many experts remain convinced

that there wasn't a single Boston Strangler,

that there were probably multiple killers

copying each other.

More than six decades later,

the Boston Strangler case still fascinates,

not only for what we know,

but for the mysteries that linger.

I'm Laurence Fishburne.

Thank you for watching History's Greatest Mysteries.