Is there anyway to find out if someone has served in our Military?

I met this guy who claims he was in the USMC, even went as far as getting a tattoo of a Bulldog on his calf. Now here's the kicker, I tried to help him out with a resume @ 50yrs of age through Gov.jobs and he wouldn't claim a Veteran's preference. He still lives w/ his Mom and Dad since his divorce and has been unemployed for over 2 years. Respectfully.....He has 2 teenage boys who are subject to his B_llsh_t! .