I think shooting was not planned. Incapacitate or kill in a bloodless manner - strangle with a cord from behind, or blow to the head (orange guy is a plastic mallet? They sell those in home depot) and may be tie up with tape. Or do so at the gun point. I'm nd you, they based on super sucker and bullmann observations they had either 2-3 or 5-10 minutes to transfer MS to Yukon. I'd say Tim Bosma was incapacitated either right after they left Bosma's residence or on Trinity road north of super sucker (depending on whether the 9:15 and 9:20 RAM sightings are Bosma's truck)
MS fks up by either not strangling enough and missing vitals, or not delivering sufficient blows, or doesn't tie well enough. They drive up Paris Rd, Tim Bosma regains consciousness or releases himself partially, may be breaks the window? DM has to immediately pull to oak park Rd (it's an over 90degree turn, not a good place for non urgent pull over) and pulls handgun keeping in his left hand. Driving down oak park he sees houses left and right, can't shoot ( mind you, 380 produces a muzzle report of over 157 dB). Finally he crosses the railroad and sees an industrial area and he shoots while still moving. He breaks almost immediately, yukon nearly rears the pickup. Possibly the first shot hits the window, second shot severes the carotid artery and Bosma dies a horrible death within 15-20 seconds. Blood all over. MS and DM assess the situation, and decide to move quickly. Possibly cover the body with tarp or repositioning so that it's less visible. But not moving to the trunk. Heavy bleeding would on the ground would prompt a 911 call next morning. Guaranteed, soil from the ditch was tested for blood. DM and MS do not know the area because instead of going around the block they make a U-turn, which doesn't save any time, looks suspicious, and given MS being a novice driver and the unpaved shoulder may lead to more trouble. My interpretation
Detailed theory, thanks. BTW "soil from the ditch was tested for blood" - did this detail actually come up in the trial?
The idea that MS struck or choked TB from behind soon after starting the test drive seems plausible. I think TB could have been incapacitated or restrained physically or with the gun prior to dropping off the Yukon driver (now in my mind it makes sense for the Yukon driver to be MS because DM drove the Dodge in the beginning and he would want to keep control of his 'prize'). It also explains why they couldn't take a chance with IT despite having 1 or 2 firearms. MS is so small and weak looking, though. Could DM count on MS's physical ability against any victim (even with the element of surprise and rear-seat advantage)?
However the idea of DM shooting while driving and while trying to navigate to an isolated location is somewhat far-fetched. I think that shooting in close quarters while driving would be very difficult to do unless TB was very groggy from being struck/choked or was partially tied. I think it is more likely that the Dodge was stationary during the shooting (if it was the driver who shot). So I can believe that the shooting occurred in the Dodge on the spur of the moment as TB started to wake/escape/fight. I just think that if it occurred while driving, it would be difficult (not impossible) for the driver to shoot (and this could have ended happier). E.g what a happy turn of events if they had attacked IT instead and he had pummelled and disarmed them.
if TB was choked/struck in the Dodge then these tools (rope/mallet) would need to be in DM's satchel initially (couldn't be hidden in MS's hoody pouch) - so DM hands the satchel to MS at start of drive - "here Mark, hold this for me"