It's having the mindset which says he's streets ahead of the rest of the pack intellectually. He banked on either NOT being believed OR, if there WERE doubts, being given the benefit.....................which is actually what they did. I'd say it was clever.
I'd have called it dumb myself. After the tragedy,Jeremy did EVERYTHING that aroused suspicion,down to him being caught. He may as well have given himself up and be done with.
RWB had a private investigator follow Jeremy. The drug squad were at his home on the day of the funeral because it's been said he was as high as a kite after the murders. His behaviour which everyone followed. Did he REALLY think that all these things would go unnoticed ?