A 50-year-old man has been convicted of fatally shooting a mother, son and a family friend at a central Kansas City house.

Anthony Walker of Kansas City was convicted Monday of three counts of first-degree murder in the January 2012 deaths of 62-year-old Donna Pike, her 41-year-old son Herschel Pike, and 57-year-old Edward Williams. He also was convicted of three counts of armed criminal action and one count of first-degree burglary.

The killings happened at the Pikes' home. Prosecutors say Williams was shot when he went to the home to check on the Pikes.

Prosecutors say an undercover police officer later purchased the murder weapon from Walker.

Walker already is serving 30 years in federal prison after he was convicted of being a felon in possession of a firearm.

DanHenson1, ThinkStock