Overview

Last seen: August 15, 1993
Location: Wishek, North Dakota
Age: 31
Status: Missing; authorities believe Anderson and Kristin Diede were homicide victims.

Main circumstances: Anderson and Diede traveled from Minnesota to North Dakota in connection with Diede’s children and an ongoing custody dispute. They were last seen in the Wishek area on August 15. Five days later, the Dodge van they had been using was found abandoned in Aberdeen, South Dakota. Neither has been heard from since, and no remains have been publicly identified as theirs.

Detailed Case Breakdown

Robert Michael Anderson: The 1993 Disappearance From Wishek, North Dakota

Robert Michael “Bob” Anderson disappeared from Wishek, North Dakota, on August 15, 1993, while traveling with his girlfriend, Kristin Joy Diede. More than three decades later, neither Anderson nor Diede has been found. North Dakota authorities list the pair as missing persons and state that investigators believe they were homicide victims. Their disappearances remain active, unsolved cold cases.

Brief Case Summary

Last seen: August 15, 1993
Location: Wishek, North Dakota
Age: 31
Status: Missing; authorities believe Anderson and Kristin Diede were homicide victims.

Main circumstances: Anderson and Diede traveled from Minnesota to North Dakota in connection with Diede’s children and an ongoing custody dispute. They were last seen in the Wishek area on August 15. Five days later, the Dodge van they had been using was found abandoned in Aberdeen, South Dakota. Neither has been heard from since, and no remains have been publicly identified as theirs.

A Trip to North Dakota Ends in a Disappearance

In August 1993, Robert Michael Anderson traveled with his girlfriend, Kristin Joy Diede, from Minnesota to Wishek, North Dakota. Diede was separated from her husband and was dealing with a difficult custody situation involving her children.

According to case summaries, Anderson and Diede took Diede’s son and daughter to their paternal grandparents in the Wishek area. Diede later told friends that she was having trouble getting the children back. The couple also visited Diede’s brother before they disappeared.

Additional reporting about their final day says Anderson and Diede spoke with a North Dakota Highway Patrol trooper about child-custody laws. They reportedly indicated that they planned to retrieve the children and return to Minnesota. They were not known to have returned home.

The Last Known Sightings in Wishek

The official North Dakota cold-case listing states that Anderson and Diede were last seen in Wishek on August 15, 1993. A 2016 report from the McIntosh County Star-Tribune provided a more specific account, reporting that the couple was last seen during the late afternoon while traveling toward a farm north of Wishek.

After that afternoon, there is no confirmed public account of either Anderson or Diede being seen alive.

Their sudden disappearance was particularly concerning because they left belongings behind in Minnesota and Diede’s family did not believe she would voluntarily abandon her children. Authorities initially considered the possibility that the couple had left voluntarily, but the investigation eventually moved toward suspected foul play.

Anderson’s Van Is Found in Aberdeen, South Dakota

One of the case’s most important pieces of physical evidence appeared approximately five days after the couple disappeared.

On August 20, 1993, the Dodge van associated with Anderson and Diede was discovered abandoned at or near a railroad parking area in Aberdeen, South Dakota, more than 100 miles from Wishek.

Some secondary case reporting states that the van’s license plates were missing and identifying information on the vehicle had apparently been altered or damaged. Those details have been repeatedly cited as circumstances supporting suspicions that the van was deliberately abandoned rather than simply left because of a mechanical problem.

The 2022 Dakota Spotlight investigation reported that the 1979 Dodge B200 van continued to be held as evidence in Logan County decades after the disappearance.

Who drove the van from the Wishek area to Aberdeen—and whether Anderson and Diede were ever inside it after August 15—remain central unanswered questions.

Investigators Came to Suspect Homicide

The North Dakota Attorney General’s cold-case page now states that Anderson and Diede are believed to have been homicide victims. No bodies have been recovered publicly, however, and no one has been convicted of causing their deaths.

That distinction is important: Anderson’s official status remains that of a missing person, even though investigators have concluded that the evidence and circumstances point toward homicide.

The state’s cold-case cases are considered active investigations. The Attorney General’s Office explains that records and additional investigative information generally cannot be released because the investigations remain open.

The Custody Conflict and People Examined by Investigators

Diede’s marital and custody situation became an important part of the investigation. Reporting in the Dakota Spotlight series documented that her marriage had deteriorated before she vanished and that a court had imposed a no-contact order following a domestic-assault conviction involving her husband. Friends interviewed for the series described Diede as fearful during the period before her disappearance.

The series also reported that Diede’s husband encountered her at the family farm near Wishek during the same weekend she and Anderson vanished. Investigators scrutinized him during the investigation, and at one point authorities used legal proceedings to obtain a hair sample from him.

Those facts do not establish responsibility for Anderson and Diede’s disappearance. No publicly identified person has been charged with killing the couple, and theories discussed in investigative reporting should not be treated as findings of guilt.

Renewed Attention to the Cold Case

The disappearance received renewed public attention in 2022 through Dakota Spotlight: Vanishing Act – The Untold Story of Kristin Joy Diede and Bob Anderson. Journalists James Wolner and Jeremy Fugleberg reconstructed the couple’s final days, interviewed people connected to the case and examined several competing theories about what may have happened.

The series revisited the abandoned van, allegations surrounding activity at the Diede farmstead, investigative steps taken by law enforcement and interviews with people who had been questioned about the case. Its final episodes emphasized that multiple theories remained possible and that the publicly available evidence did not establish who killed Anderson and Diede or precisely where they died.

Public interest has also been sustained by Anderson’s and Diede’s families. In 2016, family members announced a $5,000 reward for the discovery of human remains confirmed to belong to either missing person. Anderson’s son said at the time that the family strongly believed the couple died near Wishek on August 15, 1993. That statement reflected the family’s belief, not a publicly established finding concerning the location of their deaths.

Latest Publicly Available Case Information

Robert Michael Anderson remains listed in North Dakota’s current missing-person database, with August 15, 1993, recorded as his disappearance date and the Logan County Sheriff’s Office identified as the responsible local agency.

The North Dakota Attorney General continues to include Anderson and Diede among the state’s cold cases and describes the investigation as active. The state directs anyone with information to the Logan County Sheriff’s Office or the North Dakota Bureau of Criminal Investigation.

The Charley Project updated Anderson’s case page on February 4, 2026, including an additional photograph, while continuing to report that Anderson and Diede are missing and believed to have been homicide victims.

The Doe Network has also continued maintaining the case. Anderson was added as case 5693DMND in February 2022, the record was updated in 2024, and the organization’s current update log shows another case-information update for both Anderson and Diede.

As of the latest publicly available information reviewed, there has been no announced recovery of Anderson or Diede, no publicly announced arrest, and no criminal charge identifying who was responsible for their disappearance or presumed deaths. The case therefore remains an active North Dakota cold case more than three decades after the couple vanished.

The Questions That Remain

The abandoned van remains one of the strongest physical links in the case. Investigators still must account for how a vehicle associated with two people last seen in Wishek came to be abandoned in Aberdeen days later.

There are equally significant unanswered questions about what occurred after Anderson and Diede were last seen near Wishek, whether they ever left the area alive, where their remains may be located and whether someone else transported the van to South Dakota.

Until physical evidence, a credible witness or other new information provides those answers, the disappearance of Robert Michael Anderson and Kristin Joy Diede remains one of North Dakota’s longstanding unsolved missing-person cases.

Anyone with information—even information that seemed insignificant in 1993—is encouraged to contact the Logan County Sheriff’s Office or the North Dakota Bureau of Criminal Investigation.