we're going to meet christie walsh, going to meet her mother who hasn't spoken to her son in a few years.. >> today, family in here, they lost their son, brother, nephew, just down the street under the ben franklin bridge. homeless, college graduate, great kid. >> i can relate. we're going to go save him. >> when did you guys first see a change in your brother? >> a change? a long time ago. i would say right after he graduated college, actually. a little more distant and isolated. from there, up until this point, he's very smart. >> what did he start using? when did he start using? how fast did that get out of hand? >> i couldn't tell you how fast because he kept it secret very, very well. there were a lot of lies, it was pills, percoset. it was oxy, and when he was arrested in my kitchen in june of 2015, the officers let me know it's heroin. >> wow. >> and i was floored. i had not a clue. >> i'm kind of thinking that the approach might be the present. i think four of us should try to track him down,ing and the sight of the family members that he hasn't seen in quite a long time will spa