[Travis McGee]

Good point, the killer could be a sniper on foot or another vehicle far away, and the vehicle descriptions given are misidentifications of vehicles near the victims.

[Hatteras]

For what it's worth. On one of the local TV News websites I saw a video clip of the scene around the victim with the lawnmower. There were 3 evidence markers on the sidewalk between 10 and 20 feet from the lawnmower. The suggestion from the reporter was that he believed they were shell casings.