Teenager Conrad Roy III was feeling scared and vulnerable when he got out of his idling vehicle and text messaged a friend from the car park of a suburban shopping centre in the US last year.
Mr Roy, 18, had driven to the K-Mart in Fairhaven, in Massachusetts, with the intention of taking his life, police will allege. His vehicle was filling with carbon monoxide.
But police say he climbed out of the vehicle at the last moment and contacted his friend, Michelle Carter, to tell her he was having second thoughts.
The test message that came back allegedly read: "Get back in".
Ms Carter, 18, was charged this month with involuntary manslaughter over the death of Mr Roy, whose body was found in his vehicle in July last year. Authorities said he died of carbon monoxide poisoning.
Gregg Miliote, a spokesman for the Bristol District Attorney's Office, released a statement saying police would allege that Ms Carter had first-hand knowledge of Mr Roy's suicidal thoughts.
"Instead of attempting to assist him or notify his family or school officials, Ms Carter is alleged to have strongly influenced his decision to take his own life, encouraged him to commit suicide and guided him in his engagement of activities which led to his death," the statement said.
Court documents show more than 1000 text messages were sent between Ms Carter and Mr Roy in the week before his death.
Police allege Ms Carter urged Mr Roy to kill himself in those text messages, according to the Fairhaven Neighbourhood News. Ms Carter also questioned her friend repeatedly as to when and why he had not done it yet, according to the court documents, the news organisation reported.
Following Mr Roy's death, Ms Carter posted messages on social media saying she missed her friend, while she also organised a fundraising baseball event in his honour.
The event, called Homers for Conrad, was to raise awareness of mental health issues. The Sun Chronicle reported that Ms Carter publicised the event online, writing: "Life can be tough, but helping others makes it easier."
Ms Carter also posted about the outcome of the fundraiser on Twitter.
"Thank you so much to everyone who came out to support Homers for Conrad! I'm so happy to say that, with your help, we raised over $2300!" the tweet read.
Ms Carter's lawyer, Joseph Cataldo, told The Standard-Times of New Bedford that his client did not commit a crime and that the manslaughter charge would most likely be dismissed.
"This is terrible tragedy - a young man taking his own life," he told The Standard-Times.
He accused the District Attorney's Office of "trying to pin the blame on someone".
"I can't understand why they brought the charge," Mr Cataldo said. "They're trying to claim there is manslaughter, when they freely admit the boy took his own life. You can't have it both ways."
Ms Carter was 17 at the time of the alleged offence, and is being charged as a "youthful offender". That means she will be tried in juvenile court, but her trial will be open to the public, unlike typical juvenile cases.
She has been released from police custody on a $US2500 ($3200) bond, and was banned from using the internet and social media unless it was for school assignments.
She is also banned from text messaging anyone other than her parents.
Ms Carter is due in court again on April 17.
Support is available for anyone who may be distressed by phoning Lifeline 13 11 14; Mensline 1300 789 978; Kids Helpline 1800 551 800.
Fairfax Media
