a similar situation happened to me on this site a few years back.
a member here was stealing bits and pieces off local subaru and trying to sell them to people on nasioc. I went to the cops and they said they couldnt do anything w/o 100% proof it was mine (ie: hella makes XXXX amount of lights a year, how do you know its yours).
At the time we knew the kids name, address, phone #, age, and high school he went to.
he ended up confessing and giving everyone stuff back.
my suggestion. is it worth it to you to show up and confront her over this and maybe get jumped or shot by her guys watching to make sure the shady transaction goes ok? if it is make sure you atleast let someone know what you are doing. i say its not worth it if the cops wont be there.