A metal barrel found Sunday on the shore of Nevada's Lake Mead contained the remains of a man who was believed to have been killed in the late 1970s or early 1980s, according to authorities.

The Las Vegas Metropolitan Police Department suspects that the barrel may have washed up ashore due to the lake’s water levels lowering, which caused its water intake pipe to show last week for the first time.

“It’s really odd in the sense that had the lake never receded, we would never have discovered the body,” Lt. Ray Spencer of LVMPD told the New York Times on Monday.

On Tuesday, Spencer said the man died from a gunshot wound.

“We’re going to expand our time frame of the murder to the middle to late 1970s to early 80s,” Spencer said Tuesday.

There were items found in the barrel along with the body that made investigators conclude that it was from the time period. Around that time, casinos were known to have been operated by organized crime outfits. Investigators said they would “definitely not rule out” the possibility that the homicide was mafia-related.

The identity of the remains has yet to be announced.

The body was discovered by a couple who were wandering in the area. The couple shared details with a local news station and provided pictures of the corroded barrel. They referred to the remains of the body using male pronouns.

“We were docking our boat to go home and heard a woman scream,” Shawna Hollister, a witness to the discovery, told CBS affiliate KLAS-TV. “My husband walked over and found the body. His shirt and belt were the only thing we could see over his decomposing bones.”

Spencer said that officials expect more incidents like this to come up as the drought continues.

"The lake has drained dramatically over the last 15 years, it's likely that we will find additional bodies that have been dumped in Lake Mead" as the water level drops more, Spencer told CNN.

"The barrel was likely dropped hundreds of yards off the shore back then but that area is now considered the shoreline," he added.

Lake Mead, which is located about 25 miles from Las Vegas, is a reservoir in the states of Nevada and Arizona.