Unless you saw it yourself, there is little chance of getting to the root of the problem.
My suggestion is to be straight up with the "tea leaf" and make sure that he leaves the evidence there.
Any attempt to embark on a retrieval would simply sap your energy. Promises aren't worth the paper they're written on.
Plant the seed of doubt in their mind and watch their guilt organically grow.
Whatever you do, don't arbor any grudges towards them.
My suggestion is to be straight up with the "tea leaf" and make sure that he leaves the evidence there.
Any attempt to embark on a retrieval would simply sap your energy. Promises aren't worth the paper they're written on.
Plant the seed of doubt in their mind and watch their guilt organically grow.
Whatever you do, don't arbor any grudges towards them.