State Police canine units have been searching Belle Isle Marsh Reservation in East Boston Saturday after a body was found there Friday afternoon.

The investigators have been combing the area where the decomposed body was discovered, said David Procopio, a State Police spokesman.

Two walkers found the body at about 4:45 p.m. Friday on the East Boston side of the property near the Bennington Street entrance, Procopio said. It was found in a dry area, about 50 yards down a path in a clearing, he said.

Boston police and state troopers from the Revere barracks were first to arrive.

Authorities said they don’t know whether foul play was involved, but the condition of the body indicated that the person had likely been dead for a long time.

The spot where the body was found is being treated as a potential crime scene in case investigators learn the death was a homicide, State Police said.

No information was available Saturday about the person’s gender or age. The cause and manner of death are to be determined by the Office of the Chief Medical Examiner, according to a spokeswoman for Suffolk District Attorney Daniel F. Conley.

Authorities are also checking missing persons reports, State Police said.

The discovery is the third incident of a body or injured person found on the state-run reservation this year.

On May 29, Daniel Pepe, an 83-year-old East Boston man, was found suffering from a serious injury there. Pepe had sustained a head injury and couldn’t tell investigators what had happened to him before he died, authorities have said. The cause and manner of Pepe’s death have not been determined, the Suffolk district attorney’s office said.

Three days later, a 67-year-old Lynn man was found injured in the reservation. Police charged Michael Bruzzese with the assault on the Lynn man in early June. At the time of his arrest, authorities said Bruzzese forcibly took the man’s keys from his pocket and then stole between $250 and $300 from his wallet inside his car.

Bruzzese pleaded not guilty at his arraignment in East Boston Municipal Court.

The preliminary investigation into the body discovered Friday afternoon does not appear to be connected to the previous assault and death investigations, Procopio said.

In June, the force announced plans to increase patrols in the area and urged visitors to avoid being alone, stay alert of their surroundings, and keep cellphones charged in case of emergency.

Laura Crimaldi can be reached at laura.crimaldi@globe.com. Follow her on Twitter @lauracrimaldi.