I'm, glad the cyclist wasn't seriously injured. It sounds like the wife is more upset than the cyclist.
I wonder if the part is serialized. It would seem like a good piece to put a number onto.
Fingerprints?
Video Surveillance? It should be easy enough to spot a vehicle missing the whole front bumper cover/grill.
Alert at junkyards, repair shops, etc?
Cross cell phone data and car ownership databases?