This is tricky. Did son file a lawsuit against parent? Did son ever pay rent? I'm thinking that if son is in the Army, he should have make sure possessions were stored properly. Now that parents know there is a problem, maybe they can move their son's possessions to a more secure area - perhaps a locked closet.
Actively practicing law in Texas. Inactive licenses in Arizona and Georgia. All answers are general in nature and no attorney/client relationship exists in this forum.