Dennis Lynn Rader (born March 9, 1945) is an American serial killer who murdered ten people in Sedgwick County (in and around Wichita, Kansas), between 1974 and 1991.

He is known as the BTK killer (or the BTK strangler). “BTK” stands for “Bind, Torture, Kill”, which was his infamous signature. He sent letters describing the details of the killings to police and local news outlets during the interval in which the murders took place.

After a long hiatus in the 1990s through early 2000s, Rader resumed sending letters in 2004, leading to his 2005 arrest and subsequent guilty plea. He is currently serving 10 consecutive life sentences at El Dorado Correctional Facility in Kansas.

All of Rader’s known crimes occurred within the state of Kansas. He killed ten people in total and collected items from each murder scene. He also intended to kill others, notably Anna Williams, 63, who in 1979 escaped death by returning home much later than he expected. Rader explained during his confession that he had become obsessed with Williams and was “absolutely livid” when she evaded him. Rader spent hours waiting in her home but became impatient and left when she did not return home from visiting friends. Two of the women Rader had stalked in the 1980s and one he had stalked in the mid-1990s filed restraining orders against him; one of them also moved away.

Rader admitted in his interrogation that he had been planning to kill again. He had set a date, October 2004, and was stalking his intended victim.