even with a factory reset you still won't be able to activate it on your account.
The esn is already tied to another phone number on another account, so you, yourself will not be able to activate this phone until the line its activated on has another phone as its replacement.
Edit - and you wouldn't have to show proof of purchase?
Lol, i'm sorry, but you obviously don't know what your talking about (no offense..) if they didn't need proof of purchase or anything like that, people could just walk in with stolen equipment, (say it hasn't been reported stolen yet) and just get it activated on their account. That would not look too good on verizon's part.. He will not be able to use that phone until there is another phone to take that droids place on her account. Plain and simple.