Because of the missing money? Yes, i thought about that too...
But, I read a second source of blood was found in the back seat as well?
And why would he drive to where he was found, get out, and fall face down into water to drown?
That's what swayed me..
No, not primary because of the money, but that had a role in it.
As I indicated, JPL did not have a good relation with his boss and was on the verge of being fired. Assume that he had zero involvement with the missing money and assume that he passed the polygraph test with flying colors, for the sake of argument. DiBagio was still trying to get rid of him, and probably would have.
JPL would have to look for another job. It was reported that the money was missing. What would a future employer think if the money is missing and Luna is fired after that? Couple that with some other professional problems, like being sanctioned by a judge a day before.
I suspect that JPL wanted an excuse to leave the job, that would not cast him in a bad light. If he is "attacked by criminals" that is a good excuse to leave the job. I think he was planning to stage an attack; most of the wounds were described as "pinpricks." I suspect that one went a bit too deep.
I suspect that he had pulled into the parking lot, laid down in the back seat, to have more room, and made the cuts there. When he went too deep, he got out and attempted to follow the lights to get help; he could not see the ditch where the car ended up. He got out, possibly intending to go a house that was in line of sight, but collapsed into the ditch (stream) from loss of blood. He drowned.
I see JPL as a guy facing a great deal of stress, and not making the wisest decisions possible. I ultimately put much of the blame on DiBlagio.