Here's a hypothetical question:
There is a brand of hot sneakers all the kids are dying for. There are two kids who are friends; one is rich, one is poor. The rich kid has 10 pairs of these shoes, and the poor kid has none. They go for a walk together one night. The next day a third boy is missing and it is assumed he was killed for his shoes. His shoes are found hidden outside one of the rich boy's houses, the body found hidden at another of the rich kid's properties. Both boys are arrested and charged with the muder.
In this hypothetical situation, would one naturally assume that it was the rich boy who had come up with the idea because he wanted to have an 11th pair of the shoes? Or might one assume that it was the poor boy who might have wanted the shoes badly enough to kill for them?
Did the rich kid give a pair of his hot sneakers to his girlfriend and when they broke up he wanted his sneakers back but she refused, so he murdered her? Then he murdered his father because his father refused to buy him the 11 pair of hot sneakers? Did LE find the murdered boy's cell phone with text messages from the two other boy's discussing the hot sneakers? Maybe LE discovered the rich kid didn't buy these ten pairs of sneakers, but actually stole many pairs. What other evidence was found? Not enough information in your hypothetical scenario to render a decision in MO. Your hypothetical is comparable to only giving us this: DM and maybe MS like Dodge trucks so they go out on a test drive with the owner who is selling his. The owner TB is found murdered and burnt beyond recognition of DM's property and TB's truck is found in MB's driveway. See how that works? Not enough information. If you add more to your scenario, as MSM has in this case, maybe then it's worth rendering my opinion on your scenario. But that's JMO.
-TB's cell phone found with information on it in Brantford, related to one of the accused and on a route DM most likely travelled from TO to the farmland in Ayr numerous times,
-incinerator found on DM's property,
-TB's remains found on DM's property,
-indication of stolen vehicles/parts in the hangar,
-deceased father and ex-lover connected to DM,
-coincidentally DM paid off his condo the day after TB's disappearance,
-other test drives of Dodge Rams arranged, coincidentally DM also owned a Dodge Ram,
-identification from witnesses of accused, accused acted suspicious,
-tattoo ID'ed
-the accusation of the gun used to murder DM's father,
-DM had buddies with bad reputations/criminal histories; MWJ and MS,
-suggestion of a thrill kill,
And I'm sure there's more if anyone wants to add to this list.
DM got away with murder twice in the past and assumed he would get away with it again. He enjoyed the sensation/rush he got from murdering and eluding LE. TB's truck was an added bonus. Murdering his father was a bonus, the money he would stand to inherit from his father's estate. LB, well she just got in his way and was a thorn in his side. He wouldn't need her for sex any more because he had a girlfriend(s) who may have been jealous and always bickering at him about his "friend" LB. JMO.