A Massachusetts teenage girl was indicted earlier this month for involuntary manslaughter after investigators found she "strongly influenced" her high school friend to kill himself, CBS Boston has learned.

Bristol District attorneys say Plainville resident Michelle Carter, 18, encouraged Conrad Roy, also 18, to kill himself- even after the troubled boy showed second thoughts about taking his own life.

Roy, a student in King Philip Regional School District, poisoned himself to death with carbon monoxide inside his truck on July 13, 2014. His body was found inside the vehicle parked behind a K-Mart in Fairhaven.

"It is alleged that Mrs. Carter had firsthand knowledge of Roy's suicidal thoughts," the Bristol District Attorney's Office said, according to CBS Boston.

"Instead of attempting to assist him or notify his family or school officials, Mrs. Carter is alleged to have strongly influenced his decision to take his own life...and guided him in his engagement of activities which led to his death."

Carter was indicted for involuntary manslaughter on Feb. 5.

Investigators recovered over 1,000 text messages exchanged between Carter and Roy leading up to the moments before his death, according to court records obtained by the Fairhaven Neighborhood News.

Shortly before he died, Roy hesitated and said he was afraid of leaving his family. He got out of his truck.

"Get back in," Carter wrote in a text to Roy, according to court documents.

Carter, out on $2,500 bail, is expected to appear in New Bedford Juvenile Court in April.