South Fayette man pleads guilty to beating his mother to death

A South Fayette man accused of killing his mother three years ago pleaded guilty Wednesday to third-degree murder.

As part of a plea agreement, David Sumney, 33, is expected to be ordered to serve 20 to 40 years in state prison when he is sentenced on Nov. 17.

According to the prosecution, Margaret Sumney’s body was found on Sept. 2, 2019, after relatives asked police to conduct a welfare check.

South Fayette officers were contacted after several family members tried repeatedly to reach her on Aug. 31, 2019.

According to Assistant District Attorney Michael Pradines, each time a relative would call to speak with the victim, her son would answer and say that his mother was sleeping or that she had been drinking and taking pills.

The family was also concerned, the prosecutor said, because there had been allegations in the past of David Sumney physically abusing his mother.

On Sept. 2, Margaret Sumney’s relatives called Allegheny County police dispatch nearly two dozen times, and South Fayette police were asked to go to her residence. They went to the house on Old Orchard Drive multiple times but left because they were unable to make contact with anyone.

Finally, at 11:45 p.m., they forced entry into the house, Pradines said.

Officers found the house in disarray, with blood smeared on furniture and walls and broken glass on the floor, Pradines said.

Sumney’s body was found in a bathtub on the second floor.

The medical examiner’s office said she died from blunt force trauma to her head, neck and torso.

Her scalp was covered in lacerations, and her face and body were covered in bruises. In addition, Pradines said, she had multiple fractures of each rib.

When questioned by detectives, David Sumney denied any involvement in his mother’s death. He instead said it was likely an accident or overdose.

When detectives described Ms. Sumney’s injuries, David Sumney suggested his mother had been dating a person, and that he should be investigated.

However, when officers downloaded the contents of Sumney’s cell phone, they found dozens of photos depicting his mother’s beating death.

The first photo, Pradines said, was taken at 4:50 a.m. on Aug. 30.

“In between many of the photos of the victim appear selfies of the defendant in which he is seen with blood smeared on his face, and in one photo giving a thumb’s up pose,” the prosecutor said.

Investigators also found a video on the phone taken at 2:41 a.m. on Sept. 1, 2019, Pradines said, in which David Sumney was washing his mother’s corpse in the bathtub.

In addition, he told the court that David Sumney conducted searches on his phone at 11:11 a.m. on Aug. 30, 2019, including for the phrase “‘how long does it take before a body starts to decompose.’”

During the plea hearing, Pradines told Common Pleas Judge Edward J. Borkowski that one member of Margaret Sumney’s family vocally objected to the DA’s plea offer but that the rest were in agreement with the plea calling it “the conclusion of a three year nightmare.”