Regarding the practicality of shooting himself with the crossbow; I spent some years in an archery club growing up, and did interact with crossbows as well as bows. Some styles of crossbow have a sort of lever to discharge them rather than a trigger; it would be very possible to easily fire it at yourself in that instance. And only slightly more difficult if it was a standard gun-style trigger. Once the bolt is loaded, it doesn't take much for them to discharge.
This image below is a very old crossbow but you can see the lever system I mean, that is replicated on some newer ones too. Even the trigger style one below would be very easy to shoot at yourself if you wanted to.
I agree with the other commenters that perhaps he was on the run, and then as LE closed in he tried to take the 'easy' way out, but was apprehended in the process/before the wounds caused fatality.