A year after my divorce was finalized I found out that my ex was funneling thousands of dollars into the 2 accounts held by our minor children. These were accounts on which I was the custodian and we do not share custody of the children. He then removed the monies he had funneled in, only with my youngest child he took out more money than he had ever deposited. The bank believes he accessed the accounts by creating an online banking password using my name and social security number. It is all easy to track because he was transferring in and out of his other accounts and the children had no other activity whatsoever. What do I do next?

Call the police and report him for theft
Close those accounts and open new ones that he does not know where they are at.

Were you not getting monthly statements ? To see all the money going in ?

I hadn't opened statements for months since there was no activity. When I did open them I found the problem and then called him about it. He insists he has done nothing wrong although he has verified that he moved the money in and out of the accounts and that he may have taken more than he put in.