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The fatal stabbing of a Massachusetts woman by her longtime boyfriend was witnessed by a friend of the woman's teenage daughter who had been video chatting with the girl on an iPad, a prosecutor said Monday.

The details were released in Woburn District Court as Christopher Piantedosi, 39, was arraigned on a murder charge in the death of Kristen Pulisciano, 38, of Burlington, Mass.

Assistant District Attorney Nicole Allain said Piantedosi chased Pulisciano into their daughter's bedroom and stabbed her 34 times Thursday. A male friend whom the daughter had been video chatting with saw and heard parts of the attack in real time on his iPad, Allain said.

"He could hear the victim saying, ‘Please, please.' He could hear the daughter yelling, ‘No. No,'" Allain said in court Monday, according to the Union Leader.

"He then heard the defendant say, ‘You gotta die. You gotta die.' He then heard the victim say, ‘Chris, please stop. I love you,' and then the defendant began stabbing Kristen numerous times," Allain said.

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In a digital age of Skyping and video chatting, the alleged viewing of the killing on an iPad presents many new possibilities -- and challenges -- in trying such cases in court, legal experts told the Boston Herald.

"Obviously, the key question here is whether this data was saved on the electronic device or if the prosecution is going to rely on what the witness says they saw on a computer screen. There’s a big difference between the two,” attorney William Korman told the newspaper. "As we all know, eyewitnesses can say they saw one thing, when they saw another. If they knew the alleged perpetrator, it’s a much more difficult case."

Defense attorney Jeffrey Denner called Web evidence "just one more step in a horrible direction," according to the newspaper.

"Welcome to the worst aspect of the 21st century: cyber horror and its progeny," he told the Herald.

Prosecutors did not say in court Monday whether they captured forensic proof of what the girl's friend claims he saw on his iPad.

Authorities said the couple had a longstanding relationship but were not living together at the time. Their teenage daughter called 911 to report that her father had stabbed her mother.

Allain said Piantedosi had tried to commit suicide in the days before the attack. He reportedly told a court clinician that he suffers from bipolar disorder and attempted suicide on April 29. The Union Leader reported that he had been living with his parents for the past six weeks.

Piantedosi, who was ordered held without bail, is due back in court June 7 for a probable cause hearing.

Last year, he was dubbed the "remorseful robber" by police after he returned cash and a GPS he had taken from a woman's cart at a grocery store in Plaistow, N.H.

Click for more on this story from the Boston Herald.

The Associated Press contributed to this report.