How do I find out if a person qualifies for VA pension while collecting Social Security and a federal annuity?

My client now collects Social Security. But his primary source of income is his federal annuity. He worked for the federal government for over 25 years. However, he served during the Korean War and was honorably discharged. I would like to know under what conditions he might qualify for a VA pension benefit? I have not been able to find a clear answer doing online research. I know this may seem like greed. But I need to help his family plan for the future.