High school and camp friends of Michelle Carter testified Wednesday morning that she told them she was on the phone with Conrad Roy as he killed himself by carbon monoxide poisoning.

Carter was a 17-year-old high school student when prosecutors say she pressured Roy into suicide and helped him research the techniques that allowed him to flood the cabin of his pickup truck with carbon monoxide in July of 2014.

Text messages between Roy and Carter show her repeatedly encouraging him to end his life, saying it would be "painless" and that it was his best option. Prosecutors have alleged she convinced him to follow through in a phone call on the day of his death, urging him to return to his vehicle after he reportedly had second thoughts and exited it.

Olivia Mosolgo, who played on a softball team with Carter, and Alexandra Ethier, who knew Carter from working at a summer camp, testified that Carter told them by text message that she was on talking with Roy when he died.

"Yeah and I was on the phone talking to him when he killed himself. I'm heard him dying," Carter texted Ethier.

"I was talking to him on the phone when he killed himself," Carter wrote to Mosolgo. "Liv, I heard him die. I just wish I got him more help."

Mosolgo testified that she talked with Carter about boys. Carter talked about Conrad as her boyfriend, but Mosolgo never met him, she told Assistant District Attorney Maryclare Flynn.

Ethier, who works at an EPE summer camp with Carter, said the two were friendly but not close. She was surprised when Carter began texting her on July 12, 2014 -- the day of Roy's death.

"I didn't know her very well at all," Ethier said.

Around 10:21 p.m. on July 12 -- hours after Carter allegedly told Roy to get back in the truck -- Carter texted Either saying her boyfriend is "going through a tough time."

"He's in a bad place right now," Carter wrote.

Carter also told her friend Samantha Boardman about the phone calls. Boardman testified Wednesday about text conversations in which Carter told her Roy's death was her fault and that she could have prevented it.