They left Bruguier's 17-year-old cousin, Tracy Dion, in the car without any explanation as to where they might be going, and their whereabouts remained unknown for the next three months.

One woman told police later that she had seen Archambeau at a New Year's Eve party, but their families never saw the couple, who had a young child together.

In early March 1993, the bodies of Archambeau and Bruguier were found in a water-filled depression between the accident site and a disused railroad right-of-way a short distance from the road.

Bruguier's body had to be identified by a tattoo as it was in an advanced state of decomposition; it was dressed in the clothes she was wearing the night of the accident, but without the shoes and glasses.

Arnold Archambeau (born 1972), a member of the Yankton Sioux Tribe, was raised on its reservation in the southeastern half of Charles Mix County, South Dakota.

Raised by his grandmother after his mother's death in his teens,[4] Archambeau was living with an aunt[5] and working at the Fort Randall Casino at the time of his disappearance.

[4] He played basketball at Marty Indian School, where he was chosen as part of an all-Native American team to tour the Soviet Union in 1990.

Deputy Sheriff Bill Youngstrom, who was among the first responders, later recalled that he had other officers walk the area up and down the road in either direction, and along the adjacent railbed, looking to see once the sun rose shortly before 8 a.m., if they had perhaps collapsed off the road, fallen through ice that covered wet areas in the depression, left some indicator of their presence or wandered past the railbed and onto the nearby lake (frozen over at the time) that shares its name with the town.

There were no signs of either Archambeau or Bruguier, and Youngstrom assumed that, as in other accidents he had investigated where a driver had been drinking and wanted to avoid a criminal charge, the two would resurface within a couple of days.

He, family members and other law enforcement personnel walked a 100-by-25-yard (91 by 23 m) area between Route 281 and the railbed several times over the next weeks but found nothing.

[9] By early March 1993, the couple's whereabouts were still unknown, and police went to the media to publicize the story in hopes of finding Archambeau and/or Bruguier.

[4] Within a week, on the morning of March 10, a motorist reported seeing a body floating in meltwater in the depression between Route 281 and the railbed about 75 ft (23 m) from the accident site.

Deputies who responded to the scene found the body of a young woman, so decomposed that it was identifiable as Bruguier only by a tattoo.

[10] The disparity between the extent to which the bodies had decomposed, and their apparent absence in the three months preceding their discovery, were not the only facts that confounded investigators.

Youngstrom told Unsolved Mysteries that a tuft of hair found on the roadside near the bodies was determined to have been Bruguier's, but it was in far better condition than it should have been if it had been there the entire time since the accident.

"[12] At a March 19 news conference, family members of both Archambeau and Bruguier in attendance, along with reporters, accused officials of racism and incompetence.

[11] Whalen also announced at the news conference that police had talked to a witness who had seen Archambeau and Bruguier get into a vehicle headed east on Route 281 shortly after the accident.

Youngstrom also revealed that several people had come to the sheriff's office saying that they had seen Archambeau and/or Bruguier after the accident and had taken polygraph tests.

[10] Another cousin of Bruguier's, who lived in Sioux Falls, thought the case might be helped if the NBC series Unsolved Mysteries covered it.

[2] Youngstrom and BIAP Dennis Simmons flew to California to take calls from viewers offering possible tips after the show.

Among the sightings reported after the accident was one by a woman who knew Archambeau and said she had seen him on New Year's Eve; she had passed her polygraph test.

Youngstrom was also checking out a call from someone in North Dakota about two men seen near a "Blazer-type vehicle" at the accident site the morning the bodies were found.

"There isn't any indication of anything else" beyond the fact of Archambeau and Bruguier's deaths, said Special Agent Matt Miller of the bureau's Sioux Falls field office.

"[3] Law enforcement has not actively investigated the case in the 21st century, but the sheriff at the time did not waver from his belief that questions remained unanswered.