They’ve all been spotted since May, at all times of day in three parts of the sprawling lake’s western corner, along a stretch of lakefront less than an hour from Las Vegas.
But nearly everything else about them is a mystery. One case is being investigated as a homicide; the manner and cause of death in the others are unknown.
"In an ideal world, the climate turns around, all the waters rise and we don't see them again," said Michael Green, a professor of history at the University of Nevada, Las Vegas, said of the remains. "But the chances are not good."
The first find was perhaps the most ominous. The National Park Service, which manages the Lake Mead National Recreation Area, said in a news release that around 3 p.m. rangers found a barrel containing human remains in Hemenway Harbor, a section of lake where a local family claims to operate the largest private marina in the United States.
Of Lake Mead's six boat launches, it is also the last to remain open as water levels fall dramatically. Federal data shows the 270 square-mile reservoir — which straddles the Nevada-Arizona border and provides water to 40 million people — at 27% capacity.
The barrel was discovered in the mud along a shoreline that appeared to have been previously submerged, NBC affiliate KSNV of Las Vegas reported.
Inside what a witness described to the station as a 50-gallon drum was person who seemed to have died from a gunshot wound in the '1970s or '80s — an estimate investigators with the Las Vegas Metropolitan Police Department developed based on the person's clothes and shoes.
Although the reservoir wasn't known as a place where organized crime figures disposed of bodies, some local experts have said the killing bears the hallmarks of a mob execution.
"A barrel has a signature of a mob hit," Geoff Schumacher, vice president of The Mob Museum in downtown Las Vegas, told the Associated Press. "Stuffing a body in a barrel. Sometimes they would dump it in the water.”
What to know about Lake Mead's water crisis
Six days later, at 2 p.m., a person at the park reported finding remains on the northwestern side of the lake, at Callville Bay, the park service said.
The agency described the remains as skeletal. Dan Kulin, a Clark County spokesperson, said in an email that they were from a man believed to be between the age of 23 and 38.
No other details were available about the find, but Kulin said the coroner's office was working to identify the man and the other remains through DNA analysis, although he warned that the sample quality could be compromised by environmental conditions and time.
Officials were also comparing their findings to information about park visitors who have been reported missing over the years, he said.
It wasn't clear how many of the remains may belong to people who have drowned at the recreation area. According to data obtained through a public records request, 101 people drowned at Lake Mead between 2007 and last year, a number that surpassed any other cause of death at the park.
The National Park Service did not respond to requests for comment.
July 25, Aug. 6
A third discovery came nearly two months later. Park visitors alerted authorities on the afternoon of July 25 to human remains at Boulder Beach, a popular stretch of shoreline known for swimming, boating and picnicking.
Kulin described the remains as "partial."
On the morning of Saturday, Aug. 6, skeletal remains were found in the same area, he said, and the coroner's office is trying to determine if the two discoveries are linked to the same person.
After watching a police dive team from Las Vegas search the lake's waters that Saturday, a local fisherman, Freddy Ramos, told NBC affiliate KSNV of Las Vegas that he was thinking of "giving up on the lake."
"I haven’t got any fish, and everywhere I go, there’s bodies," he told the station.
Nine days later, on a Monday night, more skeletal remains were found at the same beach, the park service said. The police dive team was again dispatched to assist in recovering the remains, which a visitor found in the water, and park officials contacted the coroner's officer.
No other details were available, Kulin said, except that the remains were found in the water.
On Thursday afternoon, authorities said they'd been alerted to another unsettling find — a gun located near where the body was found in the barrel.
On Twitter, Las Vegas police said a journalist discovered the weapon. Firearms are often found at the lake, a police spokesman said, and it wasn't clear if the gun is connected to the remains found on May 1.