[little jeremiah]

I was thinking that if he murdered the man, it might have been as a result of his becoming a “devout” Mozlem. Since both events seem to have happened around the same time, plus the not going to the gym any more.

[Aliska]

I don't really know, of course, but there's now an article about the murder of three men on ABC website.

There was speculation in the comments that his younger brother had started smoking pot and quit. Maybe afraid of his older brother because of his violent tendencies.