I believe he left behind some financial assets.

Unless his parents are co-owners of joint accounts, they will have to go to local surrogate court for a probate proceeding. While it is a regular proceeding for an experienced lawyer, I don't think a lay person can handle it. If you are in New York or one of a few other states, the whole process can take as long as 2 years. What I would suggest is to find a local lawyer asap while the parents are still in states to sort all the paperworks.