According to the facts to establish probably cause in the search warrants it is stated "a deceased male, identified as Jason Paul Corbett, was found lying inside the residence in the master bedroom on the main level of the home".
Although, its worth wondering, as they had a spare room, why were TM and SM sleeping in the basement?
All IMO
When I hear basement, I immediately think below ground level but I understand that basement in the USA is often spoken about as being ground level. It gets confusing when terms mean different to different people.