re: UPDATE: Idaho Murders Thread (Links inside)

My guess is he did it on THAT night because he finally worked up the courage. It's highly likely he had staked out the house before in dry runs and backed out.

The answer to the question WHY will likely never be solved. It exists inside Bryan's mind and its likely even he doesn't fully understand why he had a compulsion to kill. What's clear is that at some point in the Late summer early fall he started stalking someone attached to that house and making trips late at night to observe. His stalking snowballed into murder at some point.