Most importantly, I am sorry for your loss. If I read this correctly, you had the member's login information, and if so, you can log in to secondlife.com and delete the account by going to the dashboard, clicking Account (Under Home), and Delete Account is the last link there.
It may take some time to completely remove things from searches, but as it ws said, you can open a ticket if you need further clarification into this process. Again, i am very sorry for your loss.