Michelle Carter, who urged her boyfriend to commit suicide, found guilty in his death

In a landmark case, a Massachusetts judge has ruled that Michelle Carter, who urged her boyfriend through phone calls and text messages to kill himself, is responsible for his death.

Bristol County Juvenile Court Judge Lawrence Moniz announced Friday that Carter, 20, is guilty of involuntary manslaughter after placing Conrad Roy III in a situation that led to his suicide in 2014.

Legal experts say the decision could have national implications as courts grapple with how to apply long-standing laws as technological changes have taken interactions online. In Carter's case, the ruling suggests that in effect, she was whispering in Roy's ear, "kill yourself, kill yourself," said Laurie Levenson, a criminal law professor at Loyola Law School in Los Angeles. And it essentially says that those words can lead someone to suicide.

Carter, who could face up to 20 years in prison, will be sentenced in August. Her attorney could not be reached for comment, but he told reporters he was "disappointed," according to the Boston Globe.

While handing down the verdict Friday morning, Moniz said Roy, who was found dead from carbon monoxide poisoning on July 13, 2014, outside Boston, had followed Carter's instruction and placed himself in a "toxic environment" in his truck, where he used a gas-powered water pump to commit suicide.

Roy, 18, and Carter, who was 17 at the time, had been texting about death in the days and weeks leading up to the tragedy, according to court records. In one message, Carter told him: "You're finally going to be happy in heaven. No more pain. It's okay to be scared and it's normal. I mean, you're about to die."

Moniz, however, focused on Roy's final moments when he wavered, stepping out of the truck - and Carter told him to "Get back in." The judge said that though Carter knew Roy was in trouble, she took no action.

"She admits in a subsequent text that she did nothing - she did not call the police or Mr. Roy's family," Moniz said in court. "Finally, she did not issue a simple additional instruction: 'Get out of the truck.'"

Carter was tried in a juvenile court because she was 17 at the time of the boy's suicide. Carter waived her right to a jury trial.

Levenson, the Loyola professor, said the judge's decision does not so much set a legal precedent because it does bind other courts, but it sends a strong message that "there are new means of committing old crimes," and prosecutors will be more likely to look at those cases.

"This is one of the most extreme cases we've seen," Levenson said in a phone interview. She added the question is: "When does bullying cross over into committing a homicide?"

Martin Healy, chief legal counsel for the Massachusetts Bar Association, said that Carter sealed her own fate "through the use of her own words," according to the Boston Globe.

"The communications illustrated a deeply troubled defendant whose actions rose to the level of wanton and reckless disregard for the life of the victim," he said in a statement.

Healy said the verdict, which was captured widespread attention, will have "national implications" and is "a clarion call that seemingly remote and distant communications will not insulate individuals from heinous acts that could rise to the level of criminal culpability."

The American Civil Liberties Union of Massachusetts issued a strong rebuke, arguing the conviction violates free speech protections.

"The implications of this conviction go far beyond the tragic circumstances of Mr. Roy's death," Matthew Segal, legal director at the ACLU of Massachusetts, said in a statement. "If allowed to stand, Ms. Carter's conviction could chill important and worthwhile end-of-life discussions between loved ones across the Commonwealth."

Following the guilty verdict, Katie Rayburn, the prosecutor in the case, told reporters that though she was pleased with the ruling, "there are no winners here," according to CNN.

"Two families had been torn apart and will be affected by this for years to come," she said. "We hope the verdict will bring some closure. . . . It's been an extremely emotionally draining process for everyone involved."

Roy and Carter met in 2011 and later struck up a romantic relationship - mostly online. Her attorney said they had met only a few times in person over the course of two years before Roy's death.

Roy had a history of depression and had attempted suicide in the past, but his family was hopeful he would get through it. However, police said text messages they recovered suggest that by 2014, Carter had tired of Roy's idle talk of suicide and wanted him to go through with it.

Weeks before Roy committed suicide, he texted Carter, telling her, "we should be like Romeo and Juliet at the end," according to court documents.

"F- - - NO! WE ARE NOT DYING," she responded.

Days before his death, Carter urged him to get help. "But the mental hospital would help you. I know you don't think it would but I'm telling you, if you give them a chance, they can save your life," she wrote. "Part of me wants you to try something and fail just so you can go get help."

But eventually, Carter's tone appeared to change.

On July 12, 2014, a day before Roy was found dead, Carter wrote: "So I guess you aren't gonna do it then, all that for nothing. … I'm just confused like you were so ready and determined."

"I am gonna eventually," Roy responded. "I really don't know what I'm waiting for … but I have everything lined up."

"No, you're not, Conrad. Last night was it. You keep pushing it off and you say you'll do it but u never do. Its always gonna be that way if u don't take action," Carter replied. "You're just making it harder on yourself by pushing it off, you just have to do it."

"If u don't do it now you're never gonna do it," she added.

Carter was indicted in 2015 and appealed, taking the case to the state's Supreme Court. Last summer, the court ruled that she could stand trial for her alleged role in Roy's death.

In that ruling, the court found that Carter's "virtual presence" at the time of the suicide and the "constant pressure" she had placed on Roy, who was in a delicate mental state, were enough proof for an involuntary manslaughter charge.

Her sentencing hearing is set for Aug. 3.