Smith said police consider the death "suspicious."
The man had his hands behind his head, and was lying half on the dam and half in the water. He was wearing a plain black shirt, blue-jean shorts and sandals.
There were no apparent signs of major trauma but the body did have bruises. Smith said the bruises could have occurred if the individual fell into the water.
Police were checking missing persons reports Sunday, and were canvassing bars near the creek to see whether any business owners had heard from relatives of patrons who hadn't come home, Smith said.
As he stood on the bank of the creek, Smith said the man could have drowned accidentally.
The man did not appear to have been fishing and no fishing equipment was found near the scene, he said.
"He didn't look like a sportsman," said Smith.
The man, who is believed to have been in his 20s to 40s, was white with brown hair, and of medium height and build.
In his shorts pockets police found a wallet containing about $10 and keys. Smith said he believed the keys were to a commercial building.
The man was wearing a chain and cross and a ring on the ring finger of each hand.
One of the rings had a basket-weave pattern, said Smith.
The man was wearing a working Timex watch.
Smith said investigators also found a pack of a Marlboro menthol cigarettes and a black metal fliptop lighter in his shorts pocket.
Around 3 p.m. Hagerstown firefighters climbed down the embankment to the water and lifted the body into a basket, which was then pulled to the shore.
The body was photographed and then taken to Baltimore for an autopsy.
Police were unsure of the depth of the water under the bridge or its temperature, said Smith.
The man, whose body could be clearly seen by those standing on the bridge, at first appeared to have his hands tied up over his head.
Lt. Margaret Kline said the victim was not tied and that his arms were raised over his head when rigor mortis set in.
"He froze that way," she theorized.
Hagerstown City detectives and city forensic expert Jeff Kercheval spent the afternoon scouring the banks of both sides of the creek and taking pictures. Department of Natural Resources Police helped with the investigation by going out on the water in a boat.
"They're looking for anything out of the ordinary," said Smith.
An object initially believed to be a cooler bobbing in the water was later determined to be just a piece of industrial foam and not related to the incident, he said.
The location - believed to contain largemouth and smallmouth bass and walleye - has been a popular and troublesome fishing spot for years, said Kline. People have been discouraged from fishing in the area, she said.
In past incidents:
HEIGHT="6" ALT="* "> On April 26, 1998, rescuers saved a man and two juveniles who were fishing at the creek when they ran into trouble.
Samuel Richard Long of Hagerstown, his 7-year-old son and 14-year-old nephew were fishing when their fiberglass boat got sucked in by a dam below Mount Aetna Road and capsized, sending them into the frigid water.
They held on to the boat, which was in the grip of the dam. Rescuers were able to get them out, along with a fisherman who got stuck trying to help them.
HEIGHT="6" ALT="* "> Four days later, Justin Michael Fortenberry, 23 of Frederick, Md., went to the same area to fish. He drowned after jumping in to save his dog.