You think JP has a large crucible in his shed? Or good buddies that will trust him to fire up theirs and spend a few hours alone?
When discussing body disposal it’s usually a given that the person doesn’t have easy, trustworthy access to shit like a large smelter, crematorium, medical waste incinerator or Italian fellas who own a scrap yard with an auto compactor or handy cement business that they let good friends use. Or just a BFF sexton. If they do then those are the first places to get search warrants and the first people to pull in for interviews.
I doubt JF has any friends but they are definitely checking for any family members with boats.