This happened very close to where I was living at the time, and it was all over the news. Seems like yesterday. The mother was known to be very stalker-ish of her boyfriends, and would leave Timmy with whoever would take him so she could go out. Everyone suspected her but it never got put away until now!
http://www.nj.com/middlesex/index.ss..._boy_case.html
http://www.nj.com/middlesex/index.ss..._boy_case.html