Here's what I said: "My guess......"
Which is just as good as yours.....
And by the way,
1. House locked
2. Car in garage
3. Keys left home
4. Wallet left home
4. Cell phone left home
5. Passport left home
6. Dog at home
So he either took a very, very long walk and is still walking or someone gave him a ride.......someone that he likely knew since there was no sign of struggle or forced entry in the house.
Of course there's always the chance that this was an alien abduction prior to the expected anal probe.........
How did he leave work? Did he usually drive or take public transportation? Seems unlikely he would deliberately leave his dog at home alone. But he must have arrived home from work if his personal effects were there.