I've read a bit about that. I believe that it depends on how you bury the body. Usually it takes from few months to 1-2 years for a body to decompose. And that's when you bury it in fairly shallow ground. Burying it deeper, in wet soil and inside a coffin will make the decomposition much slower. The less air can get to it, the better. So I believe this gives the body 5-10 years.
Besides, I wouldn't put it past Kinzo to not decompose completely in 2 years
