As to your comment on lint traps, I know we clean ours religiously. My husband's parents rented out their house for two years when they lived abroad. Upon return, the first time they used the dryer, it caught on fire, an uncleaned lint trap being cited as the problem.
Similarly, my sister recently ended up in the hospital for a few days. While she was hospitalized, it was the FIRST TIME her husband used the STOVE!!! They've been married 40+ years, and she's worked during all those years. I can see BM being ignorant of laundry and lint traps.
I think LE asked BM about the tranquilizer cap. Clever BM came up with a story. Then LE had a follow up question about where tranquilizer materials were. Clever BM came up with a story. When we see the order of LE questions, we may better understand how BM added bits of revealed truth to his stories.