Your MOM is complete with Opportunity. Means and Motive account for little if a suspect doesn’t have the opportunity to commit and potentially get away with the crime. I must not have a clear understanding myself of MOM because to me, opportunity is an aspect of means. But, to others, I guess means is limited to weapon and ability to use the weapon. How limited is THAT??? Means, to me, clearly implies access, but, oh, well.
Opportunity, to the rest of the world, indicates you have to have the potential to be in the crime area at the right time without an alibi. So if you don’t have a driver’s license or car, do you have the opportunity to arrive at the site of the crime? Is there no independent way of accounting for your time so you had the opportunity to be there in that time window?
Sometimes opportunity is serendipitous other times planned. When opportunity is planned, killing can move over from manslaughter to murder. Remember the importance of intent in bringing charges.
Of course, that’s why it’s MOM. All three--means, opportunity, motive--have to be in confluence to make one a viable suspect. And the detective’s job is to ensure those three solidly nail one suspect. That is maybe the major way author's complicate their mystery plots. Creating anomalies or inconsistencies in MOM causes a likely suspect to be dismissed early on. It's only when there is resolution of MOM that the murderer is revealed.
Mort reveals more of his gift in “The List”.
Obediently, he rose to do her bidding. As Mort clomped his flat-footed way down the front steps of the deck to the beach road, Fran sipped her wine and lit the last of the cigarettes in her pack. She drew the acrid air deep into her lungs and held it there, finally expelling a long, thin stream of smoke into the approaching dusk. Mort returned to find her contemplating the second key.
“And this one, Darling? What in the world is this key to?”
“That, Frieda, is the key to a co-op on the upper East Side. It’s small, just two bedrooms, but it’s right where the action is and around the corner from Le Pain Quotidien so you can eat there more often. It has a view of the Park. It also has a parking garage, and you know how hard those are to find in the City.” Mort smiled, seeming satisfied with himself and all the arrangements he had completed.