this is also the first thing that came to my mind, keeping the old wallet in his desktop, it means OP's friend is holding something, it's possible that he has an investment held there.
~snip~
We can guess as much as we want, but in the end it may just be a wallet that contains nothing. The man was curious and downloaded the BTC wallet, after some time he apparently deleted it and the wallet file remained. It was a very different time than today with a lot of doubt in BTC, and about seventy times less price than today.
If the ops have any guess that his friend have some Bitcoin in the said wallet he can check what transactions have been done on that wallet and how much balance is left in the said wallet, this then will lead him to the dead end of he doesn't have access to that wallet key's, this is very important to take note of before he may seek to fine any other further guide.
Also I wonder why the parents are so concerned that the dead guy have some investment on his laptop because most parents who does not have the computer knowledge won't point to his system as such of where to find they dead son hidden treasures.