The cell phone towers would still have a record of the “pings” showing the cell phone was on and in contact.
That would indicate there was evidence but that it was removed. IOW spoiliation of evidence which is grounds for dismissal.
I’m sure they have the info, but as you say, the problem was that it didn’t support the “official” (government) case.
It’s definitely evidence tampering - but who is going to prove it? Martin’s defense is being blocked at every turn.