Story highlights Conrad Roy, 18, was found dead of apparent carbon monoxide poisoning, police said

Police: A search of his phone found texts from a friend urging him to commit suicide

(CNN) A Massachusetts teenager faces a pretrial hearing in April on involuntary manslaughter charges for allegedly sending text messages urging a friend to commit suicide, even after he expressed second thoughts, authorities said Saturday.

Michelle Carter, 18, was indicted on February 5.

Conrad Roy, 18, of Fairhaven and Mattapoisett, Massachusetts, was found dead in his car of apparent carbon monoxide poisoning on July 13, Sgt. Kevin Kobza, public information officer for the Fairhaven Police Department, said Saturday.

At one point the night of Roy's death, he exited the vehicle and communicated to Carter that he was having second thoughts about taking his own life, Kobza told CNN. Carter then urged him via text message to get back in the car, Kobza said.

Upon searching Roy's cell phone, police discovered "hundreds" of texts between Roy and Carter, many which contained language from Carter that encouraged Roy to take his own life, Kobza said.

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