Original subtitles

Shatner: Driven by their darkest urges,

sadistic predators stalk their victims

in an effort to satisfy their need to kill.

The horrible deeds done by serial killers

give us a glimpse into the minds

of humanity's most disturbed individuals.

But what is it that separates so-called normal people

from those who have an insatiable desire

to take a life?

(gasps)

that is what we'll try and find out.

♪ ♪

detectives with cadaver dogs

discover the badly decomposed remains of several women.

They are found stuffed inside industrial barrels,

on a farm belonging to john edward robinson.

In 1993, during the early days of the internet,

robinson, under the alias "slavemaster,"

prowled chat rooms in search of potential victims.

He then lured them to his property.

As a gruesome consequence for his crimes,

john edward robinson received the dubious distinction

of being the internet's first convicted serial killer.

The internet has really opened up, uh, the opportunities

for serial killers to find, um, victims more easily.

We've had serial killers who have actually

a-attracted victims online

to their homes, where they've killed them.

Across state lines.

They've offered work. They've offered sex.

"come to my home and I'll give you money."

you know, one has to be very careful on the internet,

'cause you can be what-- whoever you want to be.

And so, serial killers do find victims that way.

-(barks) -while searching for a missing person

just off ocean parkway, in suffolk county,

a police officer and his dog discover

the skeletal remains of a dead woman.

Police later find that ten more mutilated bodies

have been disposed of in this area,

and all in a similar fashion.

Joe domanick: The suffolk county police found out

that they had a serial killer in their midst

when they started finding bodies dumped.

And really, the distinguishing thing

that we know about these killings

is that the police found out

that many of them were prostitutes.

Shatner: As news of these shocking discoveries make headlines,

the unknown murderer becomes known as

the long island serial killer.

And once the bodies are identified,

another eerie coincidence is discovered.

Several of the victims had offered escort services

on the internet site craigslist.

Hickey: Craigslist is another mask.

It's another way to use social media to find victims.

And, uh, it's another tool in their repertoire.

So, in some ways, serial killers today

are becoming more sophisticated.

Psychopaths feel a sense of power and control

because they have so many different tools

that they can use to create distractions

and to create ruses.

Narcissism and control

are two of the character traits for serial killers.

Certainly that fits for serial killers

who prey on women on the margins.

Shatner: Even though the suffolk county police have offered

a $25,000 reward for information

leading to an arrest in the long island murders--

the largest offered in the county's history--

to this day, the killer remains at large.

But what compels someone like the long island serial killer

or john edward robinson to commit cold-blooded murder

again and again?

What makes an otherwise normal human being a serial killer?

A serial killer is defined as someone who kills

three or more people

with an emotional cooling-off period in between.

Whereas a mass murderer

will come in and kill three people at the same place.

And a spree killer, he will kill,

move onto the next, kill again,

move onto the next, but there's no emotional cooling-off period.

A serial killer, it's like

he or she gets a shot of emotional heroin.

Shatner: The term "serial killer" was first coined in the mid-1970s

by former fbi psychological profiler robert ressler.

He picked the word "serial" because police described

these types of murders as being crimes in a series.

Serial killers are repetitive

because there are things that drive them.

There's a fantasy involved with-with the killing.

This is especially true if we're talking about

sexual predators who are serial killers.

Judy ho: They just don't seem to have their emotions stimulated

the way that a normal person's brain would.

They just think about what's gonna feel good right now,

and they don't routinely take other people's feelings

into consideration,

and engaging in all those analytical consequences

and functions that people think about.

Harvey rosenstock: You don't have any kind of conscience at all,

whether it's one murder or two murders or three murders.

The person who is committing a crime and another crime

and another crime, the only deterrent,

the only place where he has some qualms, some regrets,

is if, in fact, he does get caught.

Van zandt: The fbi has said there's maybe 50 serial killers

operating in the united states at any one time.

Do we have a lock on who they are? Well, no.

They would be under arrest if we did.

We don't know who they are.

We can't identify who they are.

We don't know that they're a serial killer

until we find the victims that they've killed.

We also know that when we find them, the big secret

is that we will never be able to rehabilitate them.

Shatner: If serial killers are so difficult to profile,

and nearly impossible to detect,

is there any way we can ever feel safe?

Perhaps the answers can be found by examining the case

of america's very first serial killer,

and the sadistic lair that he called

the murder castle.

An estimated 27 million people from all over the world flock

to the world's columbian exposition,

otherwise known as the chicago world's fair.

It is so named in honor of the 400th anniversary

of christopher columbus's landing in the new world.

Having risen from the ashes of the great chicago fire,

the city now shines brighter than ever,

illuminating the fairgrounds

with nearly 100,000 electric lamps.

-But... -(footsteps echoing)

lurking in the shadows is a sadistic killer...

...Herman webster mudgett,

better known by his alias h.H. Holmes.

Morrison: H.H. Holmes was extremely clever.

He was a pharmacist, actually.

His home was set up for single women

who came to the city to make their way, to get involved,

to become part of this wonderful exposition that was going on.

So h.H. Holmes had access to many, many single women...

...And he murdered them.

Hickey: Holmes had spent a great deal of time

in preparation for his murders.

It wasn't like it was on impulse.

There was a lot of control here.

I think that he enjoyed

the, uh, power he had over people in general.

And the world's fair really played out well for him.

Shatner: Holmes became rich

as a cunning and charismatic con artist.

He swindled several people out of their fortunes,

and used the proceeds to build a one-of-a-kind mansion

which allowed him to pursue his darkest desires.

The macabre edifice would eventually become known

as holmes's murder castle.

H.H. Holmes built this phenomenally complex castle

with enough rooms that he could rent rooms to people

who came in for the exposition, mostly single women,

and he would go out and advertise this,

bring people in, put them in these rooms

where they felt they were safe.

It was almost like the spider to the fly.

It was like, "come and see my mansion,

an elaborate mansion."

he had all kinds of odd staircases

-and tunnels and chutes and things. -(woman screams)

so then he would gas these victims

and then send them down the chute into the basement.

And then torture them, or if they were already dead,

then he could take-take apart the bodies and-- which he did.

Shatner: On November 17, 1894,

the man known as america's first serial killer

was finally arrested,

but only then did investigators begin to learn the full extent

of h.H. Holmes's murderous behavior.

After confessing to the murders of 27 young women,

on may 7, 1896, holmes,

now referred to by the press as "the devil in the white city"

was hanged by the neck until dead.

But what led an otherwise normal and unassuming man

to not only commit murders but to construct

such an elaborate house of horror?

Perhaps the answer can be found by exploring the lair

of yet another serial killer,

one created almost a century later.

Shatner: Police officers responding to a complaint

arrive at the apartment of a man by the name of jeffrey dahmer,

apartment number 213.

But what happens next defies explanation.

Hickey: When the police arrived at his apartment,

they went toward his bedroom, and when they opened the door,

his bedroom was full of body parts.

Torsos and heads here and there.

Shatner: The police made even more shocking discoveries:

A 57-gallon vat of acid,

photos of grotesquely mangled bodies,

partially eaten organs,

and inside the refrigerator, a human head.

In all, the apartment contained the remains of 11 human victims,

men and boys who police later determined had been murdered,

dismembered and even eaten

by the man who soon became known as

the "milwaukee monster."

jeffrey dahmer was a serial killer

who usually chose his victims, uh, in young men,

usually around their teenage years.

He would usually find a way with drugs or alcohol and sex

to compel victims to come back to his apartment,

where he would murder them.

Many times, he'd cut up the bodies.

He would save pieces of the body in his freezer

and his refrigerator.

Hickey: The stench of a decomposing body

is absolutely overwhelming, and yet,

dahmer became acclimated to it.

His fantasy was-was

to make this table, which he, which he built,

and he took the heads of some of his victims

and placed them on the desk,

where he could sit and be surrounded

by all of these skulls of people that he had eaten.

These were his friends; these were people he loved

in his own fantasy world.

Judge: Mr. Dahmer, you're charged with four counts

of first-degree intentional homicide.

-Do you understand that? -I understand, your honor.

Shatner: Like h.H. Holmes before him, jeffrey dahmer was not content

with the mere taking of human lives.

Instead, he sought to construct

the equivalent of a virtual world--

an alternate reality dedicated to his deviant fixations.

But what causes an otherwise average and unremarkable man

like jeffrey dahmer to become a bloodthirsty serial killer?

One person who believes he may have

at least a few of the answers

is graphic novelist and former dahmer classmate

john backderf.

In 2012,

nearly two decades after dahmer was beaten to death in prison,

backderf published my friend dahmer,

a series of illustrated stories that chronicle

the future serial killer's high school years.

Backderf: We went to junior high and high school together,

and were friends from age 12 to when we graduated.

He was always a pretty strange dude,

kind of an oddball, and he got darker and darker

as our time together went on.

Shatner: In his depictions of dahmer,

backderf sought to reveal the warning signs that were present

in the young, troubled man's demeanor.

Backderf: When I draw dahmer,

I try to capture the blank expression, the dead eyes.

I purposely make him look uncomfortable in his own body,

because that's how I remember him.

He was kind of, like, robotic,

like he didn't physically fit in with the rest of humanity,

which, of course, he didn't.

Jeff was very much a blank canvas.

You never knew what was going on

behind this blank wall of a face.

And of course, that's something that later became

a very lethal trait,

because his victims had no idea what was coming.

Part of dahmer's schoolyard legend

was clubhouse, where he kept roadkill

that he found around the neighborhood, small animals.

And he would keep them in pickle jars.

He would actually dissect these roadkill.

Shatner: Was dahmer's so-called clubhouse

a chilling precursor to apartment number 213,

the place where his adolescent fascination

with animal carcasses escalated

into an uncontrollable obsession of dismemberment,

necrophilia and, most notoriously, cannibalism?

We try to make sense

of something that seems so primitive

and so out of the ordinary.

A human being eating another human being?

But this is not a human being,

and he doesn't see his victim as a human being.

It's just a piece of meat.

Backderf: I never felt like I knew jeff.

I don't think anyone knew him.

I never dreamed that he would commit crimes like this.

How is it that we're so unaware

of the monsters that walk among us?

Shatner: Does jeffrey dahmer's childhood

suggest that serial killers develop their dark impulses

early in life?

And if so, then why aren't we able to spot them

before it's too late?

After more than a decade of denials,

and mere moments away from his execution,

ted bundy confesses to 30 homicides.

(woman screaming)

it was a trail of death that spanned many years

and stretched from washington state to florida.

I can only liken it to-- after, you know,

I don't want to overdramatize it--

but to have been possessed

by something so awful and so alien,

and then, the next morning, wake up from it.

Strand: He was everything, as the media loved saying,

that you would expect a fine young american man to be.

The kind of guy that women would want

to bring home to the parents.

Judge: You're a bright young man.

You'd have made a good lawyer.

I'd have loved to have you practice in front of me.

But you went another way, partner.

Strand: And yet here he was, sneaking around seattle,

with his volkswagen with the seat removed

so that he could transport bodies.

He was psychopathic.

Shatner: But how could an otherwise clean-cut

and educated young man like ted bundy

become a cold-blooded, psychopathic killer?

Van zandt: Serial killers look like any of us;

therefore they look like all of us.

There are those individuals that have the ability

to wear the mask all the time.

You can never see through that mask

until they want you to see it,

and usually that's when you've become a victim.

Morrison: When we find them,

we can't figure out why they do what they do.

How they're able to commit so many crimes

without being found.

Shatner: Perhaps an even more shocking example

of how adept serial killers can be at hiding in plain sight

can be found by examining the case of a man

who everyone thought was a selfless veteran

until they found out what he was hiding inside his house.

(siren wailing)

shatner: Police arrive at the home of anthony sowell

with a warrant to arrest him for an alleged rape.

Before they even enter the house,

they get their first hint of the horror that awaits them inside.

As soon as they open the door of the house, in the first place,

there is a... A horrific stench.

(flies buzzing)

they get up to the third floor,

and the lead officer sees dead bodies.

The bodies were so decomposed

that he couldn't even recognize them as human figures.

At that time, the county coroner came out,

started taking evidence from the scene.

It was a long night.

Shatner: In total, investigators recovered the bodies

of 11 women,

choked to death by the man who would become known

as the cleveland strangler.

Sowell committed these murders

over the course of just two years,

all without leaving his hometown

and without raising the suspicions of the community.

Sberna: The neighbors were shocked

that they were living next door to a serial killer.

He seemed like a charming, helpful, quiet, former marine.

He was named honor marine of his boot camp.

Was discharged honorably as a sergeant.

Nobody suspected what he was hiding in his house.

It was very important for him to be seen as a helper.

There were elderly people in the neighborhood

and single women that he would perform household tasks for--

mow their lawn, fix their sink.

An individual who tends to be psychopathic

can have very strong connections to the community,

and typically is very difficult to track down,

because it's a very opportunistic crime.

A person who takes advantage of a situation on the spot

to do something impulsive.

Shatner: In hindsight, sowell's efforts to portray himself

as an upstanding member of the community

were merely a cover for his evil side.

According to all accounts, he was born into a dark world

of both physical and emotional abuse.

Sberna: Anthony sowell was a product of a broken home.

He was raised by his mother and grandmother

in a large house in east cleveland.

14 people were living in that house.

His mother was physically abusive to the children.

Her favorite targets were anthony sowell's nieces.

She'd strip them naked, tie them to a banister,

then she'd whip them till they were bloody.

From an early age, he associated sex with violence.

As an adult, whipping naked women

is exactly the pattern that he recreated.

So from the earliest time that he could possibly remember,

there is no foundation of any kind of real morality.

His mother didn't particularly feel sorry for him.

Why should he feel sorry for somebody else?

Shatner: In the mid-1980s,

after serving seven years in the marine corps,

sowell returned to his childhood home in cleveland

and almost immediately found himself in trouble with the law.

He had some arrests for drinking,

drug use and breaking and enterings.

Until 1989. Met a woman.

Brought her home, took her upstairs to the third floor

where he said they were gonna party,

and then he raped her violently over a 24-hour period.

-(woman screaming) -she's able to yell and scream,

get the attention of neighbors.

She testifies against him in court.

He goes away for 15 years.

Shatner: When he was released from prison in 2005,

anthony sowell was not only an ex-con

but a registered sex offender.

So, how was he able to avoid suspicion

and commit murder practically in his own backyard,

and not once but 11 times?

Anthony sowell would, uh, charm women with his personality.

There were quite a few people that had drug problems

living in the neighborhood.

Sowell was fairly popular

because he was the man with crack.

Sowell's victims were typically african american females

who had drug problems and were transient.

Sowell was a prototypical malignant narcissist,

extremely self-absorbed to the point of committing murder

to gain whatever he needed to gain.

Many serial killers are very charming,

and that's actually how they get close to their victim,

close enough to actually do the deed.

Psychopaths are known to be able to manipulate

their social prowess, and many of them actually have

very high emotional intelligence.

It's just that they decide when they're gonna

use it and when they're not.

(echoing laughter)

morrison: Their first victim,

we don't know why they choose them.

We don't know if it's because they're available

or because they've had a thought about this.

Out of all the 50 people that may be in that bar,

why do they choose that one person

that they know will go with them?

Why and how do they know

that that individual will be cooperative?

A lot of people say it's because they're available,

they're not gonna be missed, so forth and so on,

but that's too simple an explanation.

Shatner: Today, anthony sowell resides on death row

in chillicothe correctional institution in ohio.

In addition to the 11 murders he was convicted for,

sowell is believed to have carried out

dozens of rapes and assaults

over a period of more than four decades

before he was stopped.

But did anthony sowell become a serial killer

because of the abuse he suffered at the hands of his mother?

Or was he, as some experts believe,

simply born bad?

Shatner: 15-year-old robert piest

is working the afternoon shift

at nisson pharmacy when he overhears a customer

say that he's looking for help with a remodeling job.

It will pay five dollars an hour,

almost double the pay

that piest makes at the pharmacy.

At 9:00 p.M.,

robert leaves the store to get started

for his new employer: John wayne gacy.

Van zandt: John wayne gacy ran a construction company.

And he would offer young boys jobs

for his construction company,

and, of course, they wanted to get jobs.

Hickey: He'd say, "you're looking for a job?

Come over to my house."

when the victim got there,

he'd say, "by the way, did I ever show you

the old handcuff trick?"

so, he'd put him in handcuffs

behind his back, and once that happened,

it was over.

-(siren wailing) -shatner: Ten days after

robert piest's family reported him missing,

police arrive at john gacy's home

and uncover a grisly scene.

When law enforcement went into the basement

to investigate,

they found 33 bodies in the basement.

The earth was moving, shaking everywhere

because there were millions of worms in the bodies.

It was one of the most horrific

crime scenes in american history.

Karen kuzma: During the daytime,

he led a life of running a business.

And then at night, during a period of years,

he apparently went out and killed these men.

And how often? Nobody knows.

It's still all a mystery.

Shatner: Between 1972 and 1978,

john wayne gacy

murdered at least 33 teenage boys and young men.

But perhaps even more disturbing

is the fact that often during the murders,

gacy liked to dress up like a circus clown.

It was a character he had created

for fundraising events and children's birthday parties.

Gacy's deceptions were so effective

that he once even had his picture taken

with rosalynn carter,

the first lady of the united states.

John gacy was extremely active in his community.

He would give parties, barbecues,

200 people, for all of his neighbors.

Shatner: But looming beneath gacy's baby-faced grin

and child-friendly persona was a deeply troubled man

who was plagued by a toxic mix of childhood trauma

and mental defects.

My dad was a drinker.

John was always criticized by my father.

He had a learning disability.

He had problems. They had to take him

and put him in a special school.

My father would always say to him,

you know, "you act like a sissy."

you know, "you need to be more of a man."

my mom told me that john had been sexually assaulted

when he was around eight or nine years of age.

John never said a word about his abuse or-or anything.

It's hard for me to fathom that john killed 33 young men.

But my brain tells me he had to have.

(indistinct shouting)

shatner: On may 10, 1994,

an estimated 1,000 people

gathered in the early morning hours

as the man now known as the killer clown

was executed by lethal injection.

But in the wake of his death,

one last question had to be considered.

Could john wayne gacy's dark impulses

have been genetically hardwired inside him?

Kuzma: I think everybody tries to figure out

what type of person is a serial killer.

Is this something that I have to worry about with my children

or my children's children?

Is it there in-in the genes,

or is it something that created a problem?

Shatner: In an effort to find a possible clinical explanation

for gacy's horrific crimes,

forensic psychiatrist dr. Helen morrison,

who had served as an expert witness at the trial,

made a bold request of the killer's family.

Morrison: When gacy was going to be executed,

I called the family and asked them

if we could use the brain for scientific study.

The family agreed.

Kuzma: I was really into wanting to know

was there something genetically wrong with him.

Because, I mean, there's two sisters.

Neither one of us have killed anybody.

And we wanted to get some kind of sense

of what happened, what...

How did he get this other character in him?

Morrison: This is the brain of john wayne gacy.

This is the first brain that we've been able to get

to look for any potential difference or change

that might make a serial killer.

Shatner: But could dissecting

the diseased brain of a serial killer

really offer a scientific explanation

for john wayne gacy's grotesque crimes?

Helen morrison hoped for a satisfying answer.

Morrison: Having looked at the slides of the brain,

seeing absolutely nothing abnormal,

now the thought was it's a dead brain.

What is it going to show us

about what's happening in that live brain?

We needed a living brain.

We needed to be able to study

the living brain of a serial murderer.

Shatner: According to dr. Morrison,

the only way to accurately determine

if a serial killer gene does exist

is by studying a living brain.

Many brain scans from psychopaths

show a loss of activity in the limbic system.

But is this proof that a person is predisposed to kill?

Ho: That loss of activity

in the limbic system really shows

that they have real difficulties

engaging in empathy as an automatic task.

Although we see sort of this evidence

for some hardwiring of psychopaths

in these brain differences,

we also know that nurture plays a huge role.

So, not every single person

who has sort of these psychopathic-looking brains

actually turn out to be psychopaths

in terms of their actions.

They don't necessarily commit a bunch of crimes.

Shatner: But what if one day in the future,

we are able to determine

that a serial killer gene really does exist?

What would we do with someone who has that particular gene

but hasn't yet committed any crimes?

I think the ethical problems with rewiring the brain

is the issue of the choice of the person.

When somebody says that you need to have your brain rewired,

who's making that determination?

And should they be the one to make that call?

Shatner: But even if we do eventually crack the serial killer code

and find out what compels them to kill,

we still may be powerless to stop the bloodshed.

Because how do you stop someone before they commit a crime?

Unless, of course, they want to be caught in the first place.

It seems most serial killers can't resist

playing cat and mouse with the public.

Penning letters to the police.

Leaving clues at the scene of a crime.

Even drawing maps

to where the bodies of their victims can be found.

But why?

Are they trying to prove how smart they are?

Or are they really desperate to get caught?

♪ ♪

perhaps driven by extreme narcissism,

grievance or sinister delusions,

some serial killers are compelled to communicate

with the media and law enforcement.

Like the zodiac killer,

who sent a total of 21 letters to local newspapers

that revealed specific details about his crimes.

Or david berkowitz,

who antagonized police with handwritten letters

which he signed, "yours in murder,

mr. Monster."

david berkowitz,

the so-called son of sam killer,

started his murders using a .44 caliber pistol

in new york city at the time the united states was celebrating

its 200-year anniversary.

I mean, this was a guy who said,

"look at me, look at me, look at me.

I'm the monster that you're afraid of."

and he wanted credit for his crimes.

Shatner: But why would a killer

risk being caught by engaging with

and even taunting the police?

Are they looking to become famous?

Or is there another, more twisted reason?

Dennis rader,

a.K.A. The btk serial killer out of wichita, kansas--

"btk" standing for "bind them, torture them, kill them."

I mean, this arrogance, this feeling of superiority

existed in him to the very end.

And that was the reason he was ultimately caught.

Since she lived down the street from me,

I could watch the coming and going quite easily.

Oh, I manually strangled her when she started to scream.

Dennis rader, he liked to torture victims,

psychologically and physically torture them.

-(heavy breathing) -he would stalk victims.

He'd go to their homes. He'd hide in the homes.

When people came home, he would attack them,

tie them up and then torture them,

sometimes telling them, "I might kill you, I might not kill you.

We'll see."

of course, he was going to kill them.

But he wanted them to suffer. So he's very sadistic that way.

Van zandt: Rader, over a period of 20-plus years,

was believed responsible for about ten murders,

four of which were committed on the very first night.

So here you have someone who committed a mass murder,

and he would've gotten away,

we would've never known who he was,

but he wanted to terrorize that community.

Susan peters: Good evening.

Tonight, now that we know btk is back,

the city is anxious and fearful.

A letter sent to the wichita eagle is believed

to be from the serial killer.

Dennis rader, he stopped killing for a long time.

For several years, he just stopped killing.

And then eventually he realized he was never going to be caught.

At least, in his own thinking.

And so he came back

and he started giving out information to law enforcement.

"well, here's what I'm doing. And I'm still here."

newsman: The serial killer who terrorized wichita for years

causes new fears.

Van zandt: He starts sending mementos from his crimes

to the newspaper, to law enforcement.

He sent a computer disk with some memorabilia on it.

The fbi was able to trace that computer disk

back to the church where he was an elder.

They were able to identify rader as a potential suspect.

And the btk serial killer was eventually caught.

Hickey: It was like he wanted to be caught.

He literally gave them enough information

where they could track him down.

And that's pretty unusual.

Van zandt: He wanted the reputation of btk to go on.

And because of that, because of that need within him,

he was eventually identified, arrested

and sent to jail for life.

Shatner: But did the btk killer

reemerge from the shadows in an effort to become famous

or even infamous?

Or was he really trying to be stopped

and then punished for his crimes?

Hickey: There are some, because of their narcissism,

they want to be recognized for their murders.

They're in it for the game.

They will play this all the way through.

They want movies done about them.

They want books written about them.

They want to be interviewed.

Because that's the narcissism in them.

One serial killing leads to another serial killing

that leads to another serial killing.

Because you have your moment of fame,

you go out like a shooting star.

Newswoman: Collecting sports cards is a big american hobby.

But this may, a new collectible series will go on the market:

Serial killers and mass murderers.

Shatner: There are many who believe that,

for some serial killers, the desire to be famous

is equal to their desire to kill.

But, if so, why?

Perhaps the answer can be found by using the same method

many serial killers now use to stalk their victims:

The internet.

Shatner: The internet.

For most of us, it is a powerful tool that allows us

to get vast amounts of important information

at the click of a button.

But is it also capable of making serial killing easier

and perhaps safer for the killers than ever before?

Not necessarily.

For decades, the infamous golden state killer,

who committed 13 murders in california

between 1974 and 1986

and was given several menacing names in the press,

baffled investigators.

That is, until April 24, 2018, when authorities charged

72-year-old joseph james deangelo

with first-degree murder

and identified him as the golden state killer.

And how did they finally crack the case?

An investigator uploaded crime scene dna to gedmatch,

a genealogy website that allows people

to compare their genetic information on the internet.

Authorities were able to connect information found

on the site to one of deangelo's family members,

which ultimately led the police to deangelo himself.

But does this mean that finding and apprehending serial killers

will soon become so efficient

that we will be able to stop them

before they begin their reign of terror?

It's a compelling notion but unlikely.

According to radford university's

serial killer database,

there have been more than 3,000 confirmed serial killers

in the united states since 1900.

And criminologists believe

that the united states has produced more serial killers

than any other country in the world.

But why?

Hickey: Any country has the capacity

to produce serial killers.

Uh, but there are some environments,

some cultures, like american culture,

where there's a tremendous fascination with serial killers.

Because we all want to be forensics specialists.

We love to watch all these crime movies on television.

And it makes us think about murder in very strange ways.

For most people, it doesn't create killers.

But it does fascinate people.

I do think it's true

that we're overly interested in serial killers

in this culture and that people are fascinated

by these extremes of human emotion.

Whether that contributes to copycat crimes,

that is a question that is-is worth asking.

Shatner: Is it possible that our interest in serial killers

is actually creating new ones?

It's certainly a frightening possibility

but no more disturbing than the enduring mystery

of what causes a person to hunt human beings for sport.

(woman screams)

although we know a lot about serial killers

in the united states,

there's just a lot about motivation

for human behavior that we don't understand,

that we don't know.

And that's what allows these individuals

to stay out there, stalking, identifying and killing.

Hickey: There's not one profile that fits serial killers in general.

But, actually, there are different types

of serial killers, based upon their motivations,

uh, and what drives them to kill.

So, why are humans

so endlessly fascinated by serial killers?

Are we afraid that we might become one of their victims?

Or is it something within us that makes us more afraid

that we could be serial killers ourselves?

Perhaps that's why we find them so frightening,

so-so disturbing and so...

Unexplained.

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