. >> reporter: for three years, patrick machonie used social media as his weapon. cyber talking through youtube. messages like these. i want to tie your wrists together. i'm going to follow you from work. and tweets like this one. it is up to you now to save your life. i have no options. not to mention dozens of phone calls a day. pratt worried for her life. describe what that's like, to be paranoid 24 hours a day. >> makes you question the world around you and it instills fear. >> reporter: would you check the shower? would you check the closet? >> oh, yeah, i would check all the time. i used to have dreams he found out where i lived and broke into my house and waited till i went to sleep and would kill me. >> reporter: it all began out of the blue in 2008 when machonie contacted pratt, then 19 years old. reminding her they had taken a class together at a community college. they never even officially met. she says it was initially polite. you were innocently responding to him thinking this could be a friend. >> yeah, exactly. >> reporter: about a half dozen messag