BOSTON (AP) -- A state social worker and supervisor have been fired as investigators try to determine what happened to a 5-year-old Fitchburg boy who hasn’t been seen since September.

The family had been receiving services from the Massachusetts Department of Children and Families since September, 2011 after the department received a report of neglect.

In June, officials said the social worker received a message from Jeremiah Oliver’s day care indicating his mother said he would be leaving for Florida to live with his grandmother. They say the information wasn’t confirmed by the social worker, who also failed to conduct monthly home visits.

Department of Children and Families Commissioner Olga Roche says the case represents a serious failure on the part of the social worker and supervisor.

Jeremiah’s mother and her boyfriend are both in custody.