WESTMORELAND COUNTY, Pa. -- Authorities believe a man wanted for killing an Armstrong County family killed himself Friday.

The Armstrong County District Attorney said Donald Barnhart, 31, died in an explosion following a police chase. District Attorney Scott Andreassi said Barnhart likely set off an "incendiary device" and blew up the car in which he was traveling after he noticed he was being followed by state police.

Andreassi said Barnhart, who had been wanted on three counts of criminal homicide, died at the scene of the 3 a.m. explosion on Route 819 near Route 66 in Washington Township, Westmoreland County. But officials planned to use dental records and DNA to confirm that it was Barnhart.

Barnhart was accused of killing Rhonda Walters, her husband, David Lee Walters, and their daughter, Destini. The three were found dead Tuesday in their Armstrong County mobile home.

Officials say police received a call about suspicious activity at a home near Route 819. When they arrived at the scene, they spotted a car, a maroon 1989 model, that matched the description of a vehicle taken from the Walters' home after their murders.

Meanwhile, Heather Goedicke, who is described as Barnhart's girlfriend and Rhonda Walters' youngest sister, was charged with having conspired in the murders.

Goedicke was ordered jailed Friday morning and state police charged her with three counts of conspiracy to commit criminal homicide.