Me. Rev. Stat. tit. 22, § 4039

When the court has ordered a change in the custody of a child and a person not entitled to custody refuses to relinquish physical custody to the custodian, then, at the request of the department or custodian, a law enforcement officer may take any necessary and reasonable action to obtain physical custody of the child for the rightful custodian. Necessary and reasonable action may include entering public or private property with a warrant based on probable cause to believe that the child is there.