More human skeletal remains have been found in Lake Mead just days after authorities discovered a man’s body in a barrel as unprecedented low water levels are revealing decades-old crime scenes.

Rangers from the National Park Service recovered the latest remains Saturday afternoon after receiving a witness report that they were located at Callville Bay in Lake Mead National Recreation Area.

The Clark County (Nevada) medical examiner is investigating the cause of death. The park service said an investigation is ongoing.

Lake Mead is suffering from historically low water levels, which revealed a barrel containing skeletal remains near Hemenway Harbor on May 1. Some boaters alerted the park service of the location of the body.

The body of the man found in the barrel was determied to have been shot and is suspected of being killed during the mid-1970s and early 1980s after analysis of the type of clothes and shoes he was wearing, Homicide Lt. Ray Spencer told the Las Vegas Review-Journal.

According to Spencer, the man’s shoes were sold at Kmart and manufactured in the middle and late 1970s, the news outlet reported. Spencer also said it is possible the barrel was dumped in the lake from a boat.

“The water level has dropped so much over the last 30 to 40 years that, where the person was located, if a person were to drop the barrel in the water and it sinks, you are never going to find it unless the water level drops,” Spencer told the Las Vegas Review-Journal. “The water level has dropped and made the barrel visible. The barrel did not move….It was not like the barrel washed up.”

Lake Mead reservoir is currently about 30% full and is at its lowest level since 1937, a year after Hoover Dam created it, USA Today reported. The water in the reservoir has declined to about 1,055 feet, according to the news outlet.

Police said last week that they expect more bodies to turn up in the reservoir, which stretches across the Arizona and Nevada borders. Lake Mead and Lake Powell are the largest human-made reservoirs in the U.S.

Lake Mead Drought
Lake Mead water levels are reaching historic lows amid widespread drought conditions in the Colorado River Basin. Reuters/Mario Anzuoni