A domestic incident between a brother and a sister turned deadly in Allegheny Township.By Lindsay Ward

ALLEGHENY TOWNSHIP (KDKA) — Police are investigating an overnight murder-suicide in Westmoreland County. It happened at a home along Route 356 in Allegheny Township.

A mother, in her 80s, and her two adult children, Karen and John Dufford, were inside the house at the time.

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“It’s not what most people would think as far as a traditional domestic when you get dispatched too,” said Allegheny Township Police Chief Duane Fisher.

(Photo Credit: KDKA)

The investigation began with the brother and a bonfire.

“It’s believed he was under the influence for a good portion of the day. Something happened that set him off between his sister and him related to that bonfire,” said Chief Fisher.

That then led to the sister being assaulted, and she called the police around 11:30 p.m.

Police from multiple departments started searching for John in the thick, dense woods behind his house, but they couldn’t find him.

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Investigators say the brother instead made his way to the Allegheny Township police station, picked up a phone, and asked to talk to an officer.

“We don’t know if it was a sincere effort to speak to an officer or an attempted diversionary tactic,” Chief Fisher said.

When officers made their way back, he was gone again, so the search continued. Then, around 1:40 a.m., the mother called concerned about her son. Officers made their way back to the house.

“When they were about 60 yards away from him, they heard a sudden pop and he collapsed in the front yard,” Chief Fisher said.

He had turned the gun on himself. It wasn’t until officers went inside the house that they found his sister dead after being shot numerous times.

The mother was not hurt.

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Police say besides substance abuse, mental illness is believed to be a factor.