On Showtime's series, Dexter, the titular vigilante serial killer crossed paths with all sorts of evil human beings; it was his calling to become justice when none was served, and arguably one of his best story arcs was in season four, when he faced off with the Trinity killer. Though much of Dexter was far-fetched and convoluted, show runners drew from real life inspiration when creating one of Dexter's most memorable foes.

Dexter was based on novels by writer Jeff Lindsay and ended up running on Showtime for eight seasons, beginning in 2006 and ending in 2013. In that time, Dexter managed to end the lives of over 100 victims, who were reduced down to single droplets of blood encased in a glass slide, then tucked into his wooden box as trophies. The series' fourth season, which featured Keith Carradine as Special Agent Frank Lundy and John Lithgow as Arthur Miller (the Trinity killer), was widely regarded as one of the best. Part of that rationale is because of the intense cat-and-mouse game between Dexter and Trinity that came to an explosive finale where Trinity murdered Dexter's wife, Rita (Julie Benz), and left his young son in a pool of his own mother's blood, similarly to what happened to Dexter as a child.

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While Arthur Miller's character was certainly a terrifying villain by TV standards, he only holds a candle to the real life killer that inspired him: Dennis Rader, also known as the BTK killer. BTK has been featured on numerous other shows, such as Netflix's Mindhunter, since he inspired Trinity on Dexter, but the parallels between the two create a chilling background for the fictional tale.

Dexter's Trinity Killer Was Inspired By BTK

John Lithgow in Dexter and Dennis Rader BTK Killer

Dennis Rader was born in 1945 and lived a normal, quiet life as a family man in Kansas before he became an active serial killer. This is similar to Miller's background on the show, as Dexter is first drawn to him because he seems to be a pillar of the community, a loving family man, and presents a life that Dexter very much wants to be able to mimic. This all transpires after Dexter gets married and ends up with two stepchildren as well as a baby son. Rader was truly a wolf in sheep's clothing, and went undetected for years. He started killing in 1974 and was said to have murdered ten people in the surrounding area of Wichita, Kansas between 1974 and 1991.

Trinity was named because he killed in different cities all over the country in threes: a father bludgeoned to death with a hammer, a mother pushed to her death to mimic suicide, and a young woman killed in her bathtub with a wound to her femoral artery. Trinity's victims were also family men and women, chosen to reflect his own familial trauma. Rader also targeted families, though his victimology didn't follow as stringent a pattern, and he didn't only choose families. His victims ranged in age from 9 to 62 and were both men and women. Rader got his nickname after he sent various letters and taunts to a television station, and even suggested BTK, which stands for "bind, torture, kill", as one of their options. These letters confessed to his crimes, and were attention-seeking.

However, Rader wasn't caught for these crimes until much later. After 1991, he stopped killing because he no longer had the time to plan and his familial duties as a husband, father, and community organizer held him back from continuing his murders. The case went cold, but in 2004, he started sending letters again, and the case was re-opened; Rader was arrested in 2005. After his arrest, Rader gave a list of 55 "projects" - what he called potential victims that he'd stalked over his inactive years - to Katherine Ramsland, who was writing a book about him. While certainly more forward than the Trinity killer in Dexter, Rader's crimes solidified his place as one of the worst serial killers in American history and even caught the attention of Stephen King, who based his novella, Full Dark, No Stars, on him.

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