My take on the shooting is that they continued their argument in the vehicle, the victim says something AH doesn't like, AH pulls the gun out, victim and AH struggle and the gun goes off. AH then promises money in exchange for the victim not reporting the incident.
On a side note I would never talk to police without a lawyer, I had a incident that ended up costing about 30k when it was all said and done, if the cop had admitted his mistakes instead of allowing the trial to happen it would have cost 2k. Luckily his partner told the truth and the DA was pretty incompetent.