t.j. donahue and mary petrone are diplomatic. >> she thought so. >> she was -- oh. no, i -- she could carry a tune. but she thought she was much better than she actually was. >> it didn't really matter because she -- >> it didn't. >> she had the charisma -- >> yeah. >> -- to kind of pull off anything. >> reporter: t.j. became tight with ann in high school and one day, the two of them pulled off a ferris bueller spectacular, skipping school, road-tripping all the way from springfield to new york city in her mother's car. they were 16. t.j., that's a hooky day. >> i know. i think we're try -- >> reporter: that's not just going to the movies or hanging out. >> no, no, no. it was a big deal. however, we ended up getting caught 'cause ann left the -- ticket for the george washington bridge in the car. she was impulsive like that. >> reporter: when she settled into a career, the bright lights she went for were atop an ambulance. she became a paramedic. that was another thing about ann, she wasn't all look-at-me in the spotlight. she wanted to serve, too. >> she liked help

t.j. donahue and mary petrone. >> i do know that ann loves jewelry.gs. >> gadgets, right? >> gadgets, cameras. i mean in high school, she was that same kind of person. so, she loved to spend money. >> reporter: and sometimes the spending got ahead of her. mark learned that. >> he co-signed, i think it was three total credit cards with her, one of which had racked up about a $7,000 balance at one point. >> reporter: and another thing. after ann's death, when investigators asked mark what he was doing the day of the murder, he wasn't straight with the facts. not at the beginning. first, he said he was at home that day. later, he changed his account, said he'd actually been shopping, then shared a meal >> reporter: that must make your nose twitch when a guy doesn't give you the straight out story. >> i agree. it's going to raise the suspicions a little bit. >> reporter: even though mark oleksak's story changed, investigators accepted it. he had receipts for his purchases. and the final texts between the two seemed to affirm they were close until the end,