As far as looking through building, the cops don't have the money for that. Infered can spot heat and that can be a clue but insulation takes care of that.

Oh and do you know a dogs sense of smell for drugs are only good for about 2 hours a day.
The cops don't have the money to just walk neibourhoods looking for shit to bust you with.

If they came with a warrant this is how it happened. SOMEONE NARCED him out. Otherwise they would of came for a knock and talk and wanted your permission to search or said they could smell it and had probable cause to search.

My guess is some one, even just a neighbour saw it and turned him in. I learned the hard way tooo. Just show one person and your on the list if they get busted and want a way out.

Please tell us how they went about busting him and I will tell you what happened.