The 76-year-old serial killer murdered 10 people between 1974 and 1991 and sent taunting letters to police and newspapers describing his crimes.
He also named himself the BTK Killer which is an abbreviation for 'bind, torture, kill'.
Despite being incarcerated since 2005, he manages to keep himself busy in jail and has documented his hobbies and daily routines in letters.
In one of the notes, Rader - who is serving ten consecutive life sentences at a prison in Kansas, US, meaning that he will die there - explained that he is taken care of but is living in segregation.
In a letter sent to the Daily Mail, he said: "Have TV, radio, hot-pot, books, I can call people, have visitors, just live alone and can’t have contact with others outside my cell, unless handcuff, probably listed as ‘high profile'."
He went on to add: "Work on art, poetry, write a lot of letters, keep record and book on life, exercise when I can.
"Do call close friends, that’s nice to talk to others, and they come and visit me, send me nice letters and cards, or buy books for me to read, I call them my 'Cave Family'."
In the letter, which was sent in 2019, he said: "Been here 13 years and 190 days as I write, after a while you just get tired of the same thing day after day, but keeping busy helps, also changing one’s routine."
Dr Katherine Ramsland, a professor of Forensic Psychology, has developed a relationship with Rader and spoke about this during a Q&A which was part of a documentary called BTK: Confession of a Serial Killer.
She explained how the pair developed a code system which would mean anyone reading the letters didn't understand what they were talking about.
She said: "Rader liked to imagine himself being a spy and this kind of gave him that sense that we were doing spy kinds of things which helped him to become more forthcoming."
She went on to explain that he's an 'outlier' when it comes to the stereotypes of a 'serial killer', adding: "He was a family man, so not a loner. He had a serious full time job, it wasn't just gig work.
"He was married and had kids, he was a churchgoer. He did not want to be caught - that's one of the myths about serial killers is that they secretly want to be caught, they do not.
"Certainly he's not happy that he's sitting in prison for the rest of his life."
Featured Image Credit: Sipa US/Alamy Stock Photo
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