Glensheen murders
The Glensheen murders were the murders of Elisabeth Mannering Congdon and her night nurse Velma Pietila on June 27, 1977, in Duluth, Minnesota, USA, at the Glensheen Historic Estate. The motive was initially thought to be robbery, but soon the authorities began to suspect Congdon's son-in-law Roger Caldwell and adopted daughter Marjorie Congdon. Eventually he would be convicted and she would be acquitted. Later she would be found guilty of arson and fraud, crimes for which she served prison time. Background
Chester Adgate Congdon and his wife Clara Hesperia Bannister Congdon had 7 children. In 1905, Chester began building Glensheen, a 39-room mansion on their  estate in Duluth, Minnesota. It was finished 3 years later. Chester died in 1916, and Clara many years later in 1950, upon which their daughter, Elisabeth, born April 22, 1894, inherited Glensheen. Elisabeth never married, and adopted two infants. In 1932 she adopted a daughter, Jacqueline Barnes, and renamed her Marjorie Mannering Congdon. A second daughter, Jennifer Susan Congdon (1935-2017), was adopted in 1935. Before Elisabeth's death, the family had planned to donate the Glensheen Mansion to the University of Minnesota Duluth. It was open to tours two years after the murders, but the tour guides were instructed not to speak of them. Marjorie had seven children by her first husband. She was divorced after twenty years of marriage. Marjorie moved to Colorado and married again to Roger Caldwell. At the time of her death, Elisabeth needed round-the-clock care after having a stroke. She had been confined to a wheelchair and she was paralyzed on one side. Because of her illness, her fortune was being held by a trust, and the trustees cut Marjorie and Roger off. Marjorie's own trust fund had been wiped out by spending. She and Roger had their house foreclosed and their cars repossessed. Murders
On June 27, 1977, at 7:00am, Elisabeth Congdon and her nurse Velma Pietila (born April 26, 1911) were found murdered. Pietila had been beaten to death with a candlestick, while Congdon had been suffocated with a satin pillow. Her nurse, Velma Pietila, had been a regular nurse for Mrs. Congdon until she retired. She came out of retirement to fill in for another nurse that evening. The motive was initially thought to be robbery, as the bedroom had been ransacked and there was a missing jewelry box. Pietila's missing car was discovered the next morning in the airport parking lot. Arrests
Elisabeth's daughter Marjorie became an immediate suspect as she was to receive $8 million at the time of her mother's death. Three days before Elisabeth's death, Marjorie had authorized a paper saying Roger was to receive about $2.5 million of her share. Based on evidence found at the scene and later in Roger and Marjorie's possession, they were arrested. Roger Caldwell was tried first and convicted in 1978. Marjorie was acquitted in 1979. During the trial, a key piece of evidence in Mr. Caldwell's trial, a finger print on an envelope, was contested by an expert. In addition, a witness came forward during the trial to testify to Roger Caldwell's whereabouts, though, the witness recanted after the trial. In 1982, the Minnesota Supreme Court overturned Caldwell's conviction and ordered a new trial based on the additional evidence found during Marjorie's trial. Rather than risk an acquittal at retrial, the prosecution offered him a plea deal, a confession, guilty plea to second-degree murder and time served (he had served five years of a twenty-year sentence). He confessed to both murders on July 5, 1983, and was released. He committed suicide on May 18, 1988. Marjorie's children filed a civil suit against her inheritance, arguing she was involved in the murder. She was limited to only $40,000 a year from the trust. John DeSanto, the prosecutor of the case, kept a key piece of evidence from the trial, the envelope with the fingerprint that was contested. Years later, he had it DNA tested and it was a 99% match for Roger Caldwell. Aftermath
Marjorie spent nearly two years in prison in the 1980s for arson of her own home shared with third husband, Wally Hagen, who died in 1992. Upon her release from prison, she was arrested for arson again, receiving a fifteen year sentence. About three years after her release from prison, she was arrested for computer fraud and several other counts. She pleaded guilty to fraud and removing monies from the bank account of Roger Sammis, who prior to his death had been under her care. She received three years probation in 2009. References

Further reading
Sharon D. Hendry, Glensheen's Daughter, The Marjorie Congdon Story, 1998 (10th. ed. : 2009). Gail Feichtinger with John DeSanto & Gary Waller, Will to Murder: The True Story Behind the Crimes & Trials Surrounding the Glensheen Killings, 2003 (4th. ed. June 2009). Power, Privilege, and Justice, Season 5, Episode 5, 'Mystery in the Mansion' hosted by Dominick Dunne. Aired February 2005, on CourtTV 
Joe Kimball Secrets of the Congdon Mansion: The Unofficial Guide to Glensheen and the Congdon Murders, 2017

1977 in Minnesota
1977 murders in the United States
June 1977 events in the United States