Legal drug disposal???

A distant family member is in hospital with cancer and it’s not looking good. I think we will find that he passes away soon and we family members will be cleaning out and selling his house.

Here’s where it gets weird. He is a marijuana user and we’re fairly sure there would still be some in his house. No other family members know anything about anything to do with drugs. We’d want to dispose of it safely and legally. What do we do? Wait until he passes then ask the police? Really out of our league!

EDIT: Thanks for the replies. Not sure what other drugs we’ll find. No cancer related ones as he’s been in hospital since his diagnosis and gone downhill really quickly. Don’t think he’s into other illegal drugs but we could be surprised I guess.