The incident happened back in December.
Investigators say the vet, a 27-year-old, was waiting for the check and, when it did not arrive, he notified the Treasury Department.
That's when the Marine was told the check was deposited in a Bensalem, Pa. bank on December 15th.
Police have been unable to locate the man, and are now asking for the public's help.
The suspect is described as a white male about 40 years old, 220 pounds, bald with a goatee. Police say he opened up a bank account in the Marine's name using a counterfeit driver's license.
Police say, over the course of 6 days, the man withdrew more than $22,000 from this?fraudulently opened account.?
Anyone with information is asked to call Central Detectives at 215-686-3093 or visit the Philadelphia Police Department website.