(AP) — Retired Wichita police Lt. Ken Landwehr, who supervised more than 600 homicide investigations during his career, has died at the age of 59.

KAKE-TV reported Landwehr died Monday at his home. Police Chief Norman Williams said Landwehr had kidney cancer.

Landwehr retired in 2012 after a 35-year career with the Wichita Police Department.

He investigated many of Wichita’s most infamous homicides and was credited with breaking the BTK serial killer case. The suspect, Dennis Rader, was arrested in February 2005 and pleaded guilty to killing 10 people in the Wichita area between 1974 and 1991.

Landwehr also led investigations that led to arrests in two quadruple homicides within a week of each other in 2000.