As for my take on the perps...
I'm backing the "ne'er do well" looking for esteem by taunting the police/investigators. He (or she) has been planning this for a long time. You gotta do a little recon to set up for the hits (semi-concealed position with access to swift, or at least free travel, to major traffic arteries). His ego and/or his feelings of logistical and intellectual superiority over the cops will be his undoing. However, we may be in for a long wait for the perp to slip up crudely enough to be caught.
And I think he/she will perfer to go out in a blaze of glory rather than suffer the ignobilty of apprehension.