. >> reporter: prosecutors mary clare flynn and katie rayburn laying out the case and a motive. >> ifr, she's really desperate for attention. look at me, i lost my boyfriend. >> you presented her as a girl who was manipulating, who was looking for attention. >> she wanted him to die. it appears to gain attention or to gain friendships or get girls to like her more. >> she used him as a pawn in her sick game. >> reporter: the prosecution's first witness, conrad's mom, lynn roy. >> so you said that you brought him to either a hospital in october of 2012? >> october 3rd. >> and what was the reason for that? >> because he was having suicidal thoughts. >> reporter: the prosecution calls 14 witnesses, the officer who found conrad in the parking lot. >> appears to be mr. conrad roy. >> reporter: the medical examiner who determined it was carbon monoxide that killed him. and most important, michelle carter's classmates, those girls she so desperately wanted to befriend. >> does michelle carter send you now another text that you receive later on that night? >> yes. >> and what does she tell yo