A convicted sex offender was found guilty Tuesday of strangling and stabbing a neighbor and her two teenage children.

Jurors deliberated for less than two hours before convicting James Koepp of Janesville of three counts of first-degree intentional homicide in the deaths of 38-year-old Danyetta Lentz, her 17-year-old daughter, Nicole, and her 14-year-old son, Scott. Koepp faces mandatory life in prison when sentenced April 27.

Lentz's father discovered the bodies in their trailer home in January 2007. Russell Lucht says the past few years have been difficult and he's glad jurors found Koepp guilty.

Koepp was convicted in 1983 of sexually assaulting two women at a substance abuse center and sentenced to 10 years in prison.