My ex took our children out of state with intent to keep them
We have been divorced for about 4 years now. He moved to a different state after getting out of jail(a 9 month sentence ending with a felony on his record) because I kicked him out for using drugs while on probation and living in my house. He comes to pick up our two boys one summer, then a week or two later calls me and says he wants their SS cards and birth certificates because they were going to stay there and go to school. Can he legally do that when we have joint custody? What can I do to get them back in my state?