Sidebar (as if the thread is anything else), but MM&O is a misleading criteria. You need to show a suspect has all three, but having all three doesn't make you a suspect. It just means it is possible that you did it. Lacking opportunity could rule you out, say, if you were not in the area when it was committed.
{ETA: like, you could say a cop has as much MM&O as any given suspect in a murder. Motive: he's a cop, and a psychopath by nature. Means: lots of weapons and techniques. Opportunity: just needs to be on patrol alone when it happened}
Motive is the most slippery. You could commit your crime with no actual motive other than you wanted to, yet you could have a damnn good motive but be morally impervious to the temptation. Means, well, most people could have the means to commit a lot of crimes. Opportunity can be entirely unrelated to the crime, if you happened to be around, like others were.
Even better, just the "how". Creating a single car crash with targeted fatalities is a ridiculous gamble at best.