Guns and Roses
The raygun clutched in the dead man's hand was my first clue that something weird was going on. It looked too real. And yes, plenty of people get angry at the folk crewing the tollbooths and road rage happens - to sometimes tragic effect - but the tollbooth operators don't usually shoot back.
Or if they do, it's with bullets, not rays.
The second clue of something weird going on was the roses growing all over the place. Really odd places, like out of the operator's chair (and out of his arm, but that was one for the mortician doing the autopsy)
Once the raygun had been checked over for prints, I pointed it cautiously at a patch of bare ground and pressed the trigger with a gloved finger. There was a streak of red light, and then another rose appeared, growing out of the ground where the ray had hit.
Well, that ought to make finding the culprit easier. Just follow the roses.