TIONESTA, Forest County — Scott A. Black of Butler will face the death penalty if convicted of first-degree murder in the deaths of his one-time fiancee and her boyfriend.

Forest County District Attorney Elizabeth Ziegler filed notice of aggravating circumstances, asking the court to treat the deaths as a capital case.

Black, 38, is accused of fatally stabbing Marcelle I. Edwards, 42, and Donald L. Shay, 43, of Leechburg, Armstrong County, on April 27 at Edwards’ mobile home near Tionesta.

State police allege Black showed up there and forced his way inside, stabbing Shay at least 20 times. Police said he stabbed Edwards once in the neck.

Investigators believe jealousy could be a motive in the slayings. Black and Edwards were at one time were engaged. The couple broke up in late December or January, authorities said.

Edwards and Shay began dating in February, friends said. Only days before the killings, Shay had moved in with Edwards at her home.

Black is charged with two counts each of homicide and aggravated assault, and burglary. He is in the Warren County Jail without bail.

Prosecutors in Pennsylvania must cite at least one of 18 aggravating circumstances to pursue the death penalty in a homicide.

Ziegler, in court papers filed Monday, cited three — that Black killed more than one person, that he tortured both victims, and that he killed them during a felony.

Meanwhile, Black’s formal court arraignment that was to be today was delayed until June 17 in light of the prosecution’s decision to seek the death penalty in the case.