BOSTON (WPVI) --A Massachusetts teenager charged with taunting her boyfriend to commit suicide could face trial for manslaughter.
Prosecutors say Michelle Carter used her cell phone as a tool to make her 18-year-old boyfriend take his own life.
They argue that Carter, now 18, drove Conrad Roy to kill himself, encouraging him in dozens of text messages.
Roy died of carbon monoxide poisoning in July 2014 after locking himself inside his truck in a K-Mart parking lot.
At the time, prosecutors say, he was on the phone with Carter for 47 minutes, at one point telling her he was getting out of the truck because he feared it wasn't working.
"The car was filling up, and he was scared," said prosecutor MaryClare Flynn. "She told him to get back in the car."
And just days before, in another text message, prosecutors say Carter wrote, "Don't be scared. You're finally to be happy in Heaven."
"It's inconceivable," said Claudette Roy-Viaol, Roy's great aunt. "I just don't understand how someone could do that, to encourage someone they claimed to love."
According to court documents, Roy had attempted suicide and had been hospitalized before he met Carter.
And in one text message two weeks before his suicide, he expressed his desire to take his own life. "I can't get better," he wrote. "I already made my decision."
The defense is now trying for a second time to have the involuntary manslaughter charge against Carter dropped.
"He has in fact brainwashed her to the point where she's now accepting his idea of, 'This is my only option,'" said defense attorney Joseph Cataldo.
In statement to ABC News, the defense said "Michelle's communications were by no means threatening," and that Roy "made his own conscious decision to take his own life. This is a tragedy, not a crime."