foxs julie hadden explanes. >> reporter: katherine was positive she locked up her bike with a sturdy lock. >> definitely remember locking it up when i took my lights off my bike was secured to the post, so, i just was in shock really. >> reporter: someone obviously cut her lock and stole her $850 bike she thought she would never see it again on sunday checked craig's list when she saw this ad. >> i knew that was my bike, because i have red handlebar tape that is not standard. >> reporter: she sent an e-mail to the thief. e-mailed them 6 minutes later they e-mailed back. she called police and arranged to meet the seller but she got there before police did. >> my intentions were maybe like confront them i called the police i know this is my bike but they were really big. >> reporter: she didn't want to lose the bike again. >> asked if i could take the bike for a ride, started riding it maybe i can just throw it in my car and get out of here so i did. >> reporter: police arrested 18- year-old denzel crawford, katherine said he had other stolen bikes but clearly was no criminal master mi