Massachusetts State Police found the body Mohamed Fofana, off South Boston, on the shoreline of Spectacle Island. That's directly across the water from Castle Island, where he went missing.
Mohamed's grandfather took the boy and his older sister to the park shortly after 7 p.m. Sunday. The grandfather said he was on the phone while the children were playing, and when it was time to leave, he could not find Mohamed. He reported Mohamed missing at 7:30 p.m.
Family members said Mohamed had autism and was not able to communicate with other people, WCVB reported.
"If you saw Mohamed, please help me. Help me... my little baby, please, please," the child's mother said.
A search for the Mohamed resumed on Monday. Just before 12:30 p.m., a Massachusetts State Police Marine Unit crew observed the boy's body on the shore from their boat.
Troopers from the MSP Special Emergency Response Team and State Police Detective Unit for Suffolk County were ferried to the island by the Marine Unit, and they confirmed the body to be Mohamed. State Police Crime Scene Services also responded to document the scene of the recovery.
Mohamed will be brought to shore and transferred to the custody of the Office of the Chief Medical Examiner, police said.
The State Police Detective Unit for Suffolk County is conducting a death investigation.
The video in the player above is from a previous report.