Her lawyer argues, however, that the charges should be dropped because Carter's messages are protected by free speech. According to Joseph Cataldo, the "young, impressionable girl" was "brainwashed" into supporting Roy's plan for suicide.
But in an indictment released at the weekend, prosecutors outlined in detail the extent of Carter's alleged role in helping Roy overcome his doubts. For more than a week in July 2014, the couple exchanged hundreds of messages in which Carter insisted Roy would be better off dead.
"You're finally going to be happy in heaven. No more pain," she told him in one message.
According to prosecutors, the two had struck up a romantic relationship - mostly online - in 2012. Her lawyer says they met only a few times in person.
Roy had a history of depression and had attempted suicide in the past, but his family hoped he was pulling out of it.
Text messages recovered by police suggest that by 2014, Carter had become tired of Roy's talk of suicide and wanted him to go through with it - now.
"You always say you're gonna do it, but you never do," Carter complained. "I just want to make sure tonight is the real thing." Carter was insistent, even when Roy steered the topic to other things.
Roy had doubts, and he was scared, according to his texts. What if it did not work and he ended up injured for the rest of his life? How would his family cope with the loss?
Carter had answers. He would be her guardian angel in heaven. She would comfort his family and they would move on. "There isn't anything anyone can do to save you, not even yourself," she told him.
Carter feared that Roy would make up an "excuse" to explain why his plan did not work. When Roy decided to use a different method, Carter was impatient and suggested alternatives.
The day of Roy's death - July 12, 2014 - he and Carter exchanged texts in the early hours.
"You can't think about it. You just have to do it," Carter said, telling him she did not understand why he was hesitating.
"I'm gonna eventually," he replied. "I really don't know what I'm waiting for but I have everything lined up."
They texted throughout the day about the plans, about Roy's doubts, and about Carter's insistence that "the time is right" and he was ready.
A judge will now decide whether Carter will face charges over his death. She will appear in court again on October 2.
After Roy's death, Carter became a self-proclaimed advocate for mental health. She organised a fundraising tournament in his memory and posted on Facebook and Twitter about her attempts to save his life.
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (4pm to 6pm weekdays)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• The Word
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.
