Father of fallen trooper loses battle with cancer

Paul Butterfield Sr. speaks at Sarah Knysz's sentencing.

The father of State Police trooper Paul Butterfield, who was murdered by Eric Knysz, has died.

Paul Butterfield Sr. died from cancer, the Mason County prosecutor's office confirmed.

Butterfield was present at nearly every hearing in his son's murder case.

His son was killed while on duty in Mason County in Sept. 2013. Eric Knysz was found guilty of the murder. He later killed himself in his cell at the Jackson Correctional Facility.

Trooper Butterfield was honored on Tuesday in Washington D.C. at a candlelight vigil as part of National Police Week. His name is now on a memorial honoring fallen police officers.