Additional searches are planned for a 4-year-old boy reported missing last week from a mid-Michigan Indian reservation.

Saginaw Chippewa Indian Tribe spokesman Frank Cloutier says authorities planned to regroup on Monday after search teams, the FBI, police dogs and more than 100 volunteers scoured a densely wooded area Sunday for Carnell Chamberlain off the reservation near Mount Pleasant.

Cloutier says crews on Sunday also searched ponds at a wastewater treatment plant near the child's home, but nothing significant was found.

The boy is a member of the tribe and was reported missing by his family Thursday night. The tribe has said the boy's disappearance was "suspicious."

The tribe has said the boyfriend of the boy's mother initially had not been cooperating with authorities, but was described as "minimally cooperative" Sunday.