Known as the 'BTK killer,' Dennis Rader murdered 10 people in the Wichita, Kansas, area from 1974 to 1991, often leaving clues to taunt authorities.

Who Is Dennis Rader? Born in 1945 in Pittsburg, Kansas, Dennis Rader went on to live a double life: Devoted family and company man by day, he also terrorized the Wichita, Kansas, area as the "BTK killer" — for "bind, torture, kill" — with 10 murders and brazen correspondence with authorities between 1974 and 1991. Rader's alter ego resurfaced in 2004, but his penchant for leaving clues led to his arrest and life imprisonment the following year.

Ordinary Upbringing Rader was born on March 9, 1945, in Pittsburg, Kansas, and grew up in Wichita. The oldest of four sons, he enjoyed a seemingly normal childhood, reportedly masking such disturbing behavior as hanging stray animals. Rader dropped out of college and joined the U.S. Air Force in the mid-1960s. After returning to Wichita, he married his wife, Paula, in 1971, and worked for an outdoor-supply company for about a year. In 1974, he began a lengthy stint as an employee of ADT Security Services.

First Murders On January 15, 1974, Rader strangled to death four members of the Otero family in their Wichita home—parents Joseph and Julie, and two of their children, Josephine and Joseph Jr.—before leaving with a watch and a radio. Strangulation and souvenir-taking would become part of his modus operandi, or pattern of behavior. He also left semen at the scene and later said that he derived sexual pleasure from killing. The Oteros' 15-year-old son, Charlie, came home later that day and discovered the bodies. Rader struck again a few months later: On April 4, 1974, he waited in the apartment of a young woman named Kathryn Bright, before stabbing and strangling her when she returned home. Rader also twice shot her brother, Kevin, though he survived. Kevin later described Rader as "an average-sized guy, bushy mustache, 'psychotic' eyes," according to a TIME magazine article.

'BTK' Goes Public In October 1974, Rader placed a letter in a public library book in which he took responsibility for killing the Oteros. The letter ended up with a local newspaper, and the poorly written note gave authorities some idea of who they were dealing with. Rader wrote, "It's hard to control myself. You probably call me 'psychotic with sexual perversion hang-up.'" He warned that he would strike again, noting, "The code words for me will be bind them, torture them, kill them, B.T.K." The initials stuck, and the murderer came to be known by variations of the "BTK killer" moniker, or simply "BTK." Rader's next known crimes occurred in 1977. In March of that year, he tied up and strangled Shirley Vian, after locking her children in the bathroom. In December, he strangled Nancy Fox in her home, and then called the police to report the homicide. Shortly afterward, in January 1978, Rader sent a poem to a local newspaper about the Vian killing. Several weeks later, he sent a letter to a local television station stating that he was responsible for killing Vian, Fox and another unknown victim. He also made allusions to several other notorious killers, including Ted Bundy and David Berkowitz, also known as the "Son of Sam." Despite his cat-and-mouse game with authorities, Rader was able to keep the lid on his secret, murderous life. Reportedly an attentive husband, he and his wife had a son in 1975 and a daughter in 1978. The next year, Rader graduated from Wichita State University with a degree in administration of justice. Still, he continued to taunt authorities and appeared to be poised to strike again. In April 1979, Rader waited in an elderly woman’s home but left before she returned. He sent her a letter to let her know that BTK had been there. In an effort to catch him, the authorities released the 1977 recording of his phone call to police, hoping that someone might recognize the voice. After several years without a known crime, Rader killed his neighbor Marine Hedge on April 27, 1985. Her body was found days later on the side of the road. The following year, he killed Vicki Wegerle in her home. His final known victim, Dolores Davis, was taken from her home on January 19, 1991. Dennis Rader's mugshot Photo: Sedgwick County Sheriff's Office via Getty Images