BTK was active for almost 20 years and wasn't caught until 2005.

Nine new episodes feature details from real-life cases.

Here, EW rounds up where our favorite 'Mindhunter' characters left off at the end of season 1.

It's long been thought that serial killers started life abusing and killing animals but, reports Jane Dalton, new research into the psychological effect on children who witness violence is driving action to protect people

Watch the first teaser trailer for season 2 of Netflix's Mindhunter starring Jonathan Groff with blink-and-you-miss-it shots of Charles Manson, Son of Sam (a.k.a. David Berkowitz) and a masked BTK strangler.

Former FBI special agent John Douglas, the inspiration behind Netflix’s true-crime drama “Mindhunter,” believes serial killer Todd Kohlhepp when he says there are more bodies to be discovered.

For the first time, Kerri Rawson, the daughter of the BTK serial killer Dennis Rader, has shared letters he's written to her from prison over the past 14 years, ahead of an intense interview on 20/20.

EW rounds up everything we know so far about Mindhunter season 2.

Dennis Rader, also known as the BTK Killer, is back in "Mindhunter" Season 2.

The first production images have been unveiled, revealing new and returning murderers

It's only a month away!

Today in History

A firefighter communicates with a non-verbal child using sign language in a touching moment, after checking on alarms going off in a New Hampshire apartment building.

Rosemary broke several barriers throughout her career and was the first woman to fly a tactical fighter jet.

The burglars managed to make off with a 1,000-pound safe, which contained $350,000 worth of cash and jewelry.

Plus, video shows a daycare worker forcefully dragging toddlers across the classroom.

Meanwhile, a powerful cyclone hit the West Coast with heavy rain fall.

Gov. Ralph Northam, who initially said he was in the photo, said Saturday that he was certain he wasn't in blackface or wearing a KKK costume.

Flash flood warnings are in effect up and down the state, with some places expecting up to a half a foot of rain.

"We are ready!" said 14-year MARTA veteran James Bray.

A colony of elephant seals took over a beach in Northern California during the government shutdown when there was no staff to discourage the animals from congregating in the popular tourist area.

The groundhog predicted that spring will arrive early this year.

Kerri Rawson, whose father Dennis Rader is spending the rest of his life in prison, says her kids know he is locked away but they don't know why or his full name

The families read victim impact statements before his sentencing. "I stared at him the whole time," Jeff Davis, Dolores Davis' son, told "20/20." "He didn't have the guts to look at me."

After his arrest, Dennis Rader was interviewed over the phone by Larry Hatteberg, then an anchor at ABC-affiliated station KAKE, about the murders

And the BTK killer wrote to fox digital saying the Gilfo Beach suspect was a clone of him!

BTK killer case. THERE IS A CLONE. THIS IS REAL. CLONING IS REAL. POLICE, PLEASE LOOK AT MY FILE WITH GOVERNMENT. You will find relevant evidence on my file. https://t.co/PUXTG0h5MP

Bill burr calling BTK a hack serial killer is pretty funny

RT @ProjectRemixxx: Sad this even needs to be said but: THE FAMILY MEMBERS OF THESE MONSTERS ARE VICTIMS TOO ! #Lisk #Gilgo Beach murders:…

RT @JoshBreslowTV: "They were not involved at all and that's the bottom line." As some point fingers at Rex Heuermann's family, I spoke wi…

Sad this even needs to be said but: THE FAMILY MEMBERS OF THESE MONSTERS ARE VICTIMS TOO ! #Lisk #Gilgo Beach murders: #BTK Killer's daughter on letter about #RexHeuermann... https://t.co/NFEXzUtEyz

Gilgo Beach murders: BTK Killer's daughter on letter about Rex Heuermann... https://t.co/cfFA0161LL via @YouTube

Gilgo Beach murders: BTK Killer's daughter on letter about Rex Heuermann... https://t.co/BcBLIBeAYb via @YouTube

Gilgo Beach murders: BTK Killer's daughter on letter about Rex Heuermann... https://t.co/jwazXEnGtn via @YouTube

RT @JoshBreslowTV: "They were not involved at all and that's the bottom line." As some point fingers at Rex Heuermann's family, I spoke wi…

RT @Morbidful: Dennis Rader, The BTK Killer, with his daughter in 1993 (picture taken 2 years after he had killed his last victim). https:/…

Dennis Rader, known as the BTK serial killer, told Fox News he sees "a clone of me" in Rex Heuermann https://t.co/Nx4ESG2wTN

‘I was correct’: BTK Serial Killer Calls Accused Long Island Serial Killer Rex Heuermann a Copycat Clone https://t.co/ctv3k72S3y

RT @NataliaAntonova: It’s like saying, “Well, you know, the BTK killer has some ideas worth listening to.” Bizarre to be sharing a realit…

BTK knows what a serial killer is. We prey on the most vulnerable sex workers. https://t.co/1kzcgRawSt

it's always Dahmer and Bundy too. I'd at least have a little respect if they'd get a tattoo of a real certified ugly mf like the BTK killer https://t.co/9qTEFVqltP

RT @NtimEmanovic: Where was this great piece of advise when Jeff Duhmer and the BTK killer were killing people back then ? Nobody could adv…

Where was this great piece of advise when Jeff Duhmer and the BTK killer were killing people back then ? Nobody could advise them to stop killing ! I hate you people for not doing this easy thing Coz no serial killer would exist if they were advised nOt To Kill https://t.co/lRAD1aivY0 https://t.co/uOvJYoqKL0

RT @StarlingZain: BTK KILLER SPEAKS ABOUT GILGO BEACH KILLER #serialkiller #gilgobeachserialkiller #btk #lisk #longislandserialkiller #gilg…

Hmmmm. Self-described BTK serial killer Dennis Rader was sentenced to 10 consecutive life terms. He's nothing to lose by telling us this thing is his excact clone. They learn, from the best. https://t.co/GG4IP4LSmC

Is BTK Killer Dead or Still Alive Today? Where Is The BTK Killer Now? Controversy https://t.co/kyF16qGsnV

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

BTK Killer draws comparison to gigo beach suspect

RT @KerriRawson: My dad, serial killer, Dennis Rader, calls Gilgo Beach suspect Rex Heuermann a ‘clone’ of himself “BTK and Heuermann wer…

RT @KerriRawson: My dad, serial killer, Dennis Rader, calls Gilgo Beach suspect Rex Heuermann a ‘clone’ of himself “BTK and Heuermann wer…

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

RT @KerriRawson: My dad, serial killer, Dennis Rader, calls Gilgo Beach suspect Rex Heuermann a ‘clone’ of himself “BTK and Heuermann wer…

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

RT @KerriRawson: My dad, serial killer, Dennis Rader, calls Gilgo Beach suspect Rex Heuermann a ‘clone’ of himself “BTK and Heuermann wer…

RT @KerriRawson: My dad, serial killer, Dennis Rader, calls Gilgo Beach suspect Rex Heuermann a ‘clone’ of himself “BTK and Heuermann wer…

I know it’s a terrible thing to rank and I’m sorry but I have my favorite serial killers for sure and my least favorite I like to learn more about.. my faves are BTK, Golden state killer aka EAR/ONS and LISK. Least favorite Bundy and Gacy

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

RT @Krikalitika: Takes one to know one I guess but JFC https://t.co/mTxv7Z9KXL

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

Takes one to know one I guess but JFC https://t.co/mTxv7Z9KXL

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

BTK killer on Gilgo Beach murders suspect: He is 'a clone of me' | Banfield https://t.co/OlW97tipVy via @YouTube

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

RT @KellDA: Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still…

Have you ever lived in a city where there was an active serial killer? I moved to Wichita in the late 80’s and BTK was still active.