What could have happened with Chelsea Bruck?

Here's the basic story: Chelsea Bruck went to a Halloween party in Frenchtown Township, Michigan on Saturday, dressed as Poison Ivy (from the Batman movies). She was last seen with an unidentified man at 3am on Sunday morning along Post Road, an area in Frenchtown Township. Here's a sketch of the man: 

https://twitter.com/983NashIcon/status/5274443631784…