Decades Later, DNA Revives Hope in 1987 Anoka County Cold Case

COLUMBUS, Minn. — Thirty-eight years after the body of 40-year-old Armonjean Mason was discovered along a remote stretch of County Road 23, the Anoka County Sheriff’s Office is renewing its appeal for information in one of the region’s most haunting unsolved homicides.

On Dec. 2, 1987, a passing motorist spotted Mason lying near the roadside and called 911. Deputies arrived to find her nude, with clear signs of a violent struggle. An autopsy later revealed that she had been strangled. She also suffered blunt-force trauma to the head, puncture wounds to the chest, stab wounds, and ligature marks on her wrists and ankles — indications she had been bound.

Investigators identified five persons of interest within the first year, but none were charged, and by the early 1990s, the case had gone cold. It was transferred to the Anoka County Sheriff’s Cold Case Homicide Unit, where it remained for decades.

A Breakthrough—But Not Enough

A major shift occurred in 2010, when the Minnesota Bureau of Criminal Apprehension re-examined evidence using modern forensic technology unavailable at the time of the killing. DNA specialists analyzed fingernail scrapings taken from Mason’s body and were able to isolate a Y-chromosome profile, providing a genetic marker passed through the male line.

In 2012, the Sheriff’s Office announced that the new DNA results had eliminated four of the original five persons of interest. The evidence pointed investigators toward the remaining individual on their list — a person of interest who declined to cooperate when approached by detectives.

Despite the promising forensic link, investigators acknowledged that the available DNA evidence was not strong enough on its own to support a criminal charge. The case, while no longer directionless, again stalled.

A Family’s Long Wait for Justice

Mason, a mother of two who worked as a nurse’s aide in Minneapolis, was remembered by relatives as a devoted provider. Her sister, Diane Anderson, has long called for accountability, saying at a 2012 press conference, “I’ve been praying for this day, and I hope someone will give my family closure. This case needs to be prosecuted.”

With each passing year, the family’s pleas have grown more urgent, as they continue to push for justice that has remained elusive for nearly four decades.

Investigators Renew Public Appeal

The Anoka County Sheriff’s Office continues to classify the homicide as an open and active investigation. Cold case detectives say a single tip — even one rooted in a decades-old memory — could shift the case from stalemate to breakthrough.

With the anniversary of Mason’s death prompting renewed attention, the sheriff’s office is asking anyone with information, no matter how small, to come forward.

Tips may be submitted anonymously by emailing
ACSOColdCases@anokacountymn.gov.

More information on this and other unsolved homicides can be found through the Sheriff’s Cold Case

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