It's really not that difficult to 'prove' that a shot from the ground killed von Richthofen.
In the preparation of his book 'Who Killed the Red Baron', P.J. Carisella interviewed literally hundreds of individuals WHO WERE THERE. When you consider the information supplied by these men....
Consider that: (1) EYEWITNESSES closest to the scene of the Jastas 11 & 5 / Squadron 209 dogfight are on record having seen a Camel followed by a triplane with a second Camel DIVING to fire at the triplane but NOT pursuing it. The 2nd Camel was shooting DOWNWARD as he DOVE. The Baron's death wound is right to left going forward with the front/left exit wound slightly HIGHER than the rear/right entrance wound. How could such a wound be inflicted by Brown as he DOVE on the triplane? I guess anything is possible, but this certainly describes one magic bullet. (2) Multiple eyewitnesses located further west (closer to the crash site) report only two planes flying very low, with the Camel taking extensive evasive manuevers and the triplane matching him turn for turn. All are in agreement there is no third plane at this time, as Brown had already fired and flown for home. In fact none of these observers ever even saw Brown's plane. Assuming that Brown's DOWNWARD shot had somehow travelled on an UPWARD course through the lungs/heart/aorta of von Richthofen, then we must give von Richthofen his due for continuing to match May's Camel turn for turn with his plane under perfect control. Medical science would state that a man hit through the heart would have other things to worry about. Carisella's interviews of countless individuals WHO WERE THERE leave no doubt that the triplane was under perfect control for several minutes AFTER Brown's Camel was out of the picture, following May's Camel turn for turn while firing.
Finally, if you consider the testimony of the ground gunners who actually fired on von Richthofen, as well as those who observed this fire, you get even more convincing evidence. The triplane banked immediately upon coming under fire (first recognition of being over enemy lines or MvR finally deciding the heart wound was bad enough to give up the chase 2-3 minutes after being hit?). Next the triplane turns sharply to evade bullets so that the right wings of the plane face the ground (does this make it more reasonable to believe that Brown or the ground gunners got him?). Additional shots were fired as this occured, the pilots head was observed to have jerked back, and goggles were seen to be flung off and the plane immediately came down (delayed reaction or was he just hit now?).
We are all entitled to our opinions, but I choose to believe the accounts provided by men who were there. There are more than enough of these reports on record to see that ground fire brought down the Red Baron. The only real mystery is which of the ground gunners did it?
"Close doesn't only count in horseshoes",
Roy Brown.