We're TOLD he didn't leave by any visible means of departure. LE is not mandated to disclose info if in regards to an ongoing criminal investigation.
Still, he likely didn't fall in a hole, get lost in a wall, or become boarded up in floorboards. These can be corroborated by, albeit alleged, thorough searches by multiple parties.
Back to "official"...can trained dogs miss scents? Yes. In that small of a potential hit area, and with a known possible (human) decomp, within such a short period of time? No.
He's not at UTS. IMO, he met with whoever, for whatever, and was killed/dumped that night.