Anything is possible, hopefully he will be found, however, since police didn't find any trace of foul play in the house, that seems unlikely to me. There is also the fact that there was a 4 yo in the house and the Grandmother, so I can't see them not telling.
The family is always first in the suspect frame of any missing person or death. If they are eliminated the circle spreads outwards, to friends and neighbours, then to strangers.
I doubt that some else would be described as a person of interest if there was a doubt about the closest people.
