He's done what he needs to - by reporting it to police. They really aren't just going to shrug, walk away, and say "oh well" just because the ex and her new bf lied to cover the bf's fanny. Now that a crime has been reported, it's the job of POLICE to come up with "proof". They know how to investigate such things, question other neighbors who may have overheard the ruckus out on the street that night, find holes in people's statements, etc. Investigations can take time, and criminal charges being formally brought can take months more. Your son needs to (a) concentrate on recovering from his injuries, and (b) go seek a restraining order against both the ex and her bf while the case is working it's way through the investigation. He also needs to keep all of his doctor appointments, and keep track of all of his medical bills in the event that he wants to pursue a civil case for damages, expenses, pain & suffering, etc. at a later date.

