A Massachusetts man killed his girlfriend during a botched murder-suicide in her Bucks County home, police said

A Massachusetts man killed his girlfriend in front of her children earlier this month, Bucks County prosecutors said Tuesday, ignoring one of the girls’ cries for him to stop.

Thadius McGrath, 35, then attempted to kill himself, according to the affidavit of probable cause for his arrest, shooting himself once in the head. McGrath survived, and is now charged with murder in the death of Samantha Rementer inside her home in Northampton Township.

McGrath, in an interview with county detectives Monday, admitted that he beat and strangled Rementer, 31, with the cord from a floor lamp as her children watched, the affidavit said. He said he attacked her because she had upset him.

Bucks County District Attorney Matt Weintraub, in announcing the arrest, denounced both the crime and McGrath’s attempt to avoid prosecution by shooting himself.

“I cannot think of two more cowardly acts,” Weintraub said. “He will now be made to pay an exacting price for his crimes.”

McGrath remained in custody, denied bail. There was no indication he had hired an attorney.

Police were called to Rementer’s home in Northampton on June 8 by McGrath’s mother, who had received a suicidal call from him hours earlier, the affidavit said. When the officers arrived, they were greeted by Rementer’s 5-year-old daughter, Lilly, who told them, “[Daddy] killed Mommy because she was annoying him and then [Daddy] shot himself accidentally.”

Inside the home, officers found Rementer’s 2-year-old daughter, Cassandra, still strapped in her high chair in the dining room. They found Rementer, unresponsive, on the floor of a bedroom with the cord from a floor lamp still wrapped around her neck. She had sustained blunt-force trauma to her face, and was pronounced dead at the scene by medics.

In another bedroom, the officers found McGrath lying on the floor, covered in blood, with a 9mm pistol beside him. He was taken to St. Mary Medical Center, where doctors discovered he had suffered a self-inflicted gunshot wound to his face.

McGrath’s father later told police that his son had called him earlier that day and admitted that he killed Rementer during an argument.

Rementer’s father, Bill, said in an interview Tuesday that his daughter was a caring, loving mom, who had overcome a recent tragedy: the father of her children had died of a heart attack the previous year.

Since his daughter’s death, Rementer said, he and his wife have stepped in to take care of her children, Lilly and Cassandra. And Northampton Township police have rallied around the girls as well. At Lilly’s fifth birthday party on June 11, he said, nearly half of the department showed up to help celebrate.

Detectives, he said, called the girl a “rock star,” whose poise and bravery in describing what she saw as a witness to her mother’s murder helped them to piece together key evidence against McGrath. And she told investigators she kicked and bit him as he attacked her mother.

The girls, he said, are doing well but still adjusting to life without their mother.

“We’re trying to find a new normal,” Rementer said. “I’m 68, and suddenly my wife and I are parents to a 5-year-old and 2-year-old, but we wouldn’t have it any other way.”