John Douglas is the founder of the FBI’s Behavioural Science Unit and highly regarded as a “serial killer whisperer”. The hit Netflix series ‘Mindhunter’ is based on the book by the same name which he co-authored with Mark Olshaker.

Douglas created profiles based on examining crime scenes, understanding the killer’s individual habits, and predicting their next move. His method of hunting serial killers was initially dismissed until it later proved an effective way to capture criminals.

He has interviewed some of the most violent and notorious criminals ever to have existed. Considering all the evil he has faced – these are the most terrifying of them all.

10. Jerry Brudos

Serial killer Jerry Brudos abducted and killed four women in Oregon between 1968 and 1969. Known as ‘The Shoe Fetish Slayer’, he claimed that women’s shoes were his “substitute for pornography”. He even kept the severed foot of one victim in his garage at home and took several photographs. Brudos was so frightening that actor Ted Levine based part of his performance as Buffalo Bill in ‘The Silence of the Lambs’ on the killer.

Brudos tried to plead not guilty by reason of insanity. Douglas recalled, “(Brudos) said, “‘John, I have hypoglycemia. When I have an attack, I can just kill myself accidentally because I’m just out of my mind.’ What he’s doing is giving me what you call excuse abuse. That the reason he killed all these women and cut off their foot and took pictures of them wearing high heel shoes is because of this hypoglycemia attack that he would have? If you hear something like that you kind of chuckle and then you’ll say, ‘Wait a minute. You didn’t do that.'”

9. John Wayne Gacy


John Wayne Gacy became known as ‘The Killer Clown’ after he was convicted of torturing and killing at least 33 teenage boys and men between 1972 and 1978 in Cook County, Illinois. All but four of the victims were buried in the crawl space under his house – the others were dumped in the Des Plaines River. Gacy was a successful businessman who often attended children’s parties and fundraisers dressed as his alter-ego ‘Pogo the Clown’.

Douglas said, “We used (him) as a training tool to basically show how a guy like Gacy was almost like a chameleon. How he could blend into society. He can have a job and be very, very functional, married and belong to a political party and have his picture taken with Rosalynn Carter. These people don’t look odd. They look like you and I and can blend into society. To this day, people think that serial killers look different than us, act differently than us.”

8. Dennis ‘BTK’ Rader

Between 1974 and 1991, serial killer Dennis Rader terrorized the city of Wichita, Kansas, murdering 10 people and later sent letters with details of his crimes to the media. He even gave himself the signature ‘BTK’ meaning ‘bind, torture, kill’. Rader took a ‘break’ from serial killing for nine years only to resurface years later. A devoted family man and the president of his church council, he hid his double life so well that even his wife and daughter were unaware of his twisted crimes.

John Douglas was so fascinated by the hunt for the BTK, he wrote the book, ‘Inside the Mind of BTK: The True Story Behind the Thirty-Year Hunt for the Notorious Wichita Serial Killer.’

“Sometimes you know the case so well that there’s just like one thing you want to know. With him, it was, ‘Why did you stop? And then what triggered you to start killing again?'” explained Douglas. Adding, “When the time comes to talk to the offender, you have in the back of your mind what this guy – who looks so normal – what he did.”

7. Donald Harvey

Former hospital orderly Donald ‘Angel of Death’ Harvey killed 37 patients to “ease their pain” between 1970 and 1987. Harvey even alleged that the real victim count was more likely 87 patients. The majority of his crimes took place in Marymount Hospital in London, Kentucky, and the Cincinnati V.A. Medical Hospital. He would either suffocate his victims or administer a lethal overdose of medication.

In his book, ‘The Killer Across the Table: Unlocking the Secrets of Serial Killers and Predators with the FBI’s Original Mindhunter’, Douglas revealed how Harvey was so different from other killers.

He explained, “(Harvey) didn’t have to be predatory – he didn’t have to go on the hunt. The victims were in the hospitals so he could work on certain wards where people were very sick and deathly ill. He soon found out he could kill these people, he said he was a mercy killer but he was not as some of the things he did were sadistic to the victims.”

6. Ted Bundy


Whenever serial killers are discussed there is one name that appears more than most – Ted Bundy. The cold-blooded killer, rapist, and necrophile confessed to killing 30 women and teenage girls in the 1970s. Recently there has been a renewed interest in his crimes following the release of Netflix’s docu-series ‘The Ted Bundy Tapes’ and movie ‘Extremely Wicked, Shockingly Evil and Vile.’ 

Bundy’s chameleon-like appearance and manipulative personality allowed him to avoid authorities for many years and also successfully escape prison twice. In court, he represented himself and pleaded his innocence despite the staggering evidence against him.

Douglas explained, “Really at that time there were so many people, I’m talking about educated people as well, that thought that Bundy couldn’t have done it. Because of how he is and how charismatic… that’s not the image (people think of). The image is more like Hannibal Lector, I believe in the minds of people, not a Ted Bundy.”

5. Gary Ridgway

Gary Ridgway, also known as the ‘Green River Killer’, was convicted of 49 separate murders between 1982 and 1998 in Washington Oregon. His victims were all female sex workers and runaways – he later confessed they were an easy target as nobody would report them missing.

The hunt for the Green River Killer also involved Ted Bundy who claimed the killer would likely return to the ‘dump sites’ where he left the bodies to further violate the corpses – something which was later determined to be true.

Douglas contributed to the investigation as a profiler and the hours were so grueling he was hospitalized. He said, “I collapsed during the Green River murder investigation. They recommended me going to a stress psychologist and I did. They said I was experiencing post-traumatic stress disorder. Just the volume and then the nature of dealing with the criminals and dealing with the victims.”

Finally, in 2001, Ridgway was caught and agreed to disclose the locations of many missing women in exchange for a life sentence instead of the death penalty.

4. Richard Speck

During the early hours of July 14th, 1966, Rich Speck entered South Chicago Community Hospital and brutally murdered eight nurses. The torture of the victims leading up to their deaths lasted five hours as he led the young women “like lambs to the slaughter.” One of the nurses managed to hide under a bed until the massacre was over and she later identified Speck from his “Born To Raise Hell” tattoo.

The Cook County district attorney said, “It really was the first random mass murder of the 20th century. It really was the end of an age of innocence. It changed everything. We all became much more conscious of our security. Eight nurses could be slaughtered in their beds for no reason by a stranger.” 

During his trial, Speck showed no remorse for any of his victims. Douglas interviewed Speck and when asked about the massacre, the cold-blooded killer replied, “It just wasn’t their night.”

3. Gary Heidnik

John Douglas revealed his interview with Gary Heidnik is one that still haunts him today. Heidnik had been diagnosed with schizoid personality disorder and attempted suicide 13 times whilst spending time in and out of psychiatric hospitals. Between November 1986 and March 1987, the twisted killer abducted and tortured six women – killing two – in Philadelphia, Pennsylvania.

Douglas revealed, “(Heidnik) was even worse than the guy Buffalo Bill in the movie ‘Silence of the Lambs’. (He) would fill the pit up with water and not drown (his victims) but have them stand in water up to their necks and then get electric wire and torture them while they were in the water. What made it even worse was after he killed them he then would put the victims in a meat grinder and fed (them to the other) victims.”

Heidnik was finally caught when one of his victims managed to escape. He was executed by lethal injection in 1999.

2. Wayne Williams

Between 1979 and 1981, at least 28 African-American children and adolescents were killed in a case now known as The Atlanta child murders. 23-year-old Wayne Williams was convicted of two of these murders and sentenced to life behind bars. Despite strong evidence against Williams and that following his arrest the murders had stopped – he still pleaded his innocence.

Douglas was one of the Special Agents consulted during the search for the killer and the first to advise they should be on the lookout for a black male. Douglas knew a white killer would have been too obvious in black communities and he also detailed how serial killers tend to kill within their own race.

In 2019, Atlanta’s Police Chief Erika Shields announced she will reopen many of the unsolved murders linked to the case. Shields said, “This is about being able to look these families in the eye and say, ‘We did everything we could possibly do to bring closure to your case.’ We are going make some headway, but I am not sure how much.”

1. Edmund Kemper

Edmund Kemper murdered ten victims – including both of his grandparents and his mother – in the early 1970s. Kemper also kept several of his victim’s heads after the murders before eventually disposing of them. Standing at 6 ft 9? tall, weighing over 300 lbs, and with an IQ at a genius level; he could overpower his victims both mentally and physically. Investigators labeled him a natural born killer.

Kemper’s hatred of women stemmed from the relationship with his mother who constantly made him feel worthless. Douglas explained, “Even though he was a big guy, his mother just demeaned him, degraded him, broke him down as a kid so when he went to school, being as big as he was, he was the one being bullied.

Adding, “What he did is horrific but, what I’m thinking as I’m doing the interview (with him), is he’s a result of this abusive early childhood by his mother. Had he been taken out of that environment, he could have made something or done something positive in his life but that was not the case.”