A man accused of killing his ex-wife's boyfriend in a Bedford County home pleaded guilty on Friday and will serve life in prison.

Mark Alan Shirey, 45, pleaded guilty to first-degree murder for the March 2011 shooting death of 49-year-old Michael Simpson inside his Cumberland Valley Township home.

As part of his plea, Shirey agreed to life in prison without parole to avoid a trial. He was facing the death penalty if the case went to jury.

Simpson was the new boyfriend of Shirey's ex-wife. The couple had four children together and had divorced 10 before Shirey murdered Simpson.

Bedford County District Attorney Bill Higgins told 6News that the guilty plea will spare the victim's family from hearing graphic testimony, as well as save extensive time, resources and finances that are dedicated to prosecute and defend a capital case.

"I maintain that had Mark Shirey refused to accept responsibility for his involvement in this crime, he should have been out to death," said Higgins. "His decision to accept responsibility and plea was a huge factor in our decision to forgo the death penalty."

Court officials said members of Simpson's family are expected to attend Shirey's formal sentencing expected in mid-October.