Basically, you'll have to read everything ever written on the subject, make up your own mind, then defend your decision against all those who have a contrary opinion.
Despite what has been written over the years, the precise timing of events has never been established and the bullet that inflicted the fatal wound has never been found. So, based on the evidence available, it would appear unlikely that
Roy Brown fired the fatal shot, despite what he claimed in his combat report.
However, just to liven things up, I'll say that the RAF was correct in giving Brown the credit.
Graeme