One of Rockford’s most infamous killers has died.

The Winnebago County State’s Attorney’s Office confirms Simon Peter Nelson has passed away. Nelson murdered his six children and family dog back in 1978 and was sentenced to life in prison.

State’s Attorney Joe Bruscato released a statement, saying in part:

“As always, our thoughts remain with the victim’s family and loved ones who continue to mourn the deaths of Nelson children almost 40 years ago.”

Nelson had been up for parole numerous times throughout the years, but was always denied. He was 85.