Dennis Lynn Raer (born March 9, 1945) is an American serial killer who murdered 10 people in Sedgwick County (in and around Wichita), Kansas, between 1974 and 1991. He was known as the BTK killer (or the BTK strangler), which stands for "Bind, Torture and Kill,", which describes his modus operandi. Letters were written soon after the killings to police and to local news outlets, boasting of the crimes and knowledge of details. After a long hiatus, these letters resumed in 2004, leading to his arrest in 2005 and subsequent conviction.