Joseph Edward Duncan III
Overview
Joseph Edward Duncan III was an American serial killer, kidnapper, and repeat sex offender whose criminal history stretched across several decades and multiple states. Born on February 25, 1963, Duncan became one of the most notorious child predators in the United States after his arrest in Idaho in 2005 exposed a series of murders, kidnappings, and sexual assaults reaching back to the 1990s. He was ultimately convicted of five murders and confessed to two additional child murders in Washington state for which he was never formally prosecuted.
Duncan's most notorious crimes were the May 2005 murders at the Groene family home outside Coeur d'Alene, Idaho. He killed three members of the household, kidnapped two young children, Dylan and Shasta Groene, and took them across state lines into the mountains of Montana. Dylan was later murdered, while Shasta survived and was rescued after being recognized with Duncan at a restaurant in Coeur d'Alene.
Early Criminal History
Duncan displayed violent sexual behavior while still a teenager. In 1980, at age 17, he was arrested in Washington after abducting and sexually assaulting a 14-year-old boy at gunpoint. Duncan was convicted and received a 20-year sentence. Evaluators considered him an exceptionally dangerous sexual offender, and he spent more than fourteen years confined before being released in 1994.
His release did not end his criminal behavior. Duncan repeatedly violated parole conditions and later admitted committing murders during periods when he was living outside prison. Investigators eventually discovered that crimes committed in Washington and California during the 1990s closely matched admissions Duncan made after his 2005 arrest.
Sammiejo White and Carmen Cubias
Eleven-year-old Sammiejo White and her 9-year-old half-sister, Carmen Cubias, disappeared from the Crest Motel on Aurora Avenue in Seattle, Washington, on July 6, 1996. Their disappearance remained unsolved for years. Their skeletal remains were discovered on February 10, 1998, near an abandoned property in the Bothell, Washington, area.
After Duncan was arrested in Idaho in 2005, he provided federal investigators with a detailed confession concerning two girls he said he had abducted and killed in Washington in 1996. Investigators concluded that his description referred to Sammiejo and Carmen. Duncan admitted killing the girls by striking them with a metal object.
Despite the confession, Washington authorities did not prosecute Duncan for the murders. The case therefore remained legally distinct from the murders for which he was convicted. Sammiejo White and Carmen Cubias are best described as confessed or suspected victims of Duncan rather than victims established through a criminal conviction.
The Murder of Anthony Martinez
On April 4, 1997, 10-year-old Anthony Michael Martinez was playing with other children near his home in Beaumont, California. Duncan approached the children with a story about looking for a missing cat. After gaining their attention, he produced a knife and abducted Anthony, forcing him into a vehicle before driving away.
An enormous search followed. Law enforcement agencies investigated thousands of tips, but Anthony remained missing for approximately two weeks. On April 19, 1997, a Bureau of Land Management ranger discovered the child's body among rocks in Berdoo Canyon in the Indio Hills area of Riverside County.
The exact date Anthony died could not initially be established because of the condition of his remains and exposure to the desert environment. Duncan later admitted that he had kept Anthony alive for a period after the kidnapping before attacking him and abandoning him in the desert. For that reason, April 19 is properly described as the date Anthony's body was found rather than a conclusively established date of death.
The murder remained unsolved until Duncan's arrest in Idaho. Investigators compared Duncan's fingerprints with evidence preserved from the Martinez crime scene and matched him to a fingerprint found on material used to bind Anthony. Duncan also confessed and provided information about the crime. In March 2011, he pleaded guilty in California to Anthony's kidnapping and murder and received additional life sentences without the possibility of parole.
The Minnesota Case and Duncan's Flight
By the early 2000s, Duncan was living in Fargo, North Dakota, where he was publicly identified as a high-risk registered sex offender. In 2004, he was accused of molesting a 6-year-old boy at a playground in Detroit Lakes, Minnesota, and attempting to molest another child. Formal charges followed in 2005.
Duncan appeared in court on April 5, 2005, and was released after $15,000 bail was posted. He subsequently disappeared instead of continuing through the court process. Within weeks, he was in northern Idaho, where he began watching the Groene family.
The Groene Family Murders
Duncan encountered the rural Groene residence near Wolf Lodge Bay, just outside Coeur d'Alene, Idaho. Investigators determined that he did not simply enter the home impulsively. He watched the property and learned about the household before carrying out the attack.
During the night of May 15 into May 16, 2005, Duncan entered the residence. Inside were 40-year-old Brenda Groene, her boyfriend Mark McKenzie, 37, Brenda's 13-year-old son Slade Groene, and her younger children, 9-year-old Dylan Groene and 8-year-old Shasta Groene.
Duncan restrained members of the family. He murdered Brenda Groene, Mark McKenzie, and Slade Groene by inflicting fatal blunt-force injuries. Authorities discovered their bodies at the residence on May 16, 2005. Dylan and Shasta were missing, immediately turning the triple homicide into a major kidnapping investigation.
The Kidnapping of Dylan and Shasta Groene
Duncan took Dylan and Shasta from Idaho in a stolen vehicle and drove them into remote areas of western Montana. He eventually kept the children at an isolated campsite in the Lolo National Forest. For weeks, Duncan held both children captive and subjected them to repeated physical and sexual abuse.
During the captivity, Duncan murdered Dylan. The precise calendar date of Dylan's death has not been publicly established with certainty. He was alive when abducted on May 16, 2005, and was killed before Duncan's arrest on July 2, 2005. Duncan admitted shooting the 9-year-old and attempting to conceal evidence of the murder at the campsite.
Dylan's remains were discovered at the remote Montana campsite on July 4, 2005. Authorities subsequently confirmed through identification procedures that the remains belonged to Dylan.
Shasta Groene's Rescue and Duncan's Arrest
Shasta remained alive after her brother's murder. In the early morning hours of July 2, 2005, Duncan entered a Denny's restaurant in Coeur d'Alene with Shasta. Employees and customers recognized the child from the extensive publicity surrounding her disappearance.
Restaurant employees quietly contacted authorities while keeping Duncan from realizing that he had been recognized. Police arrived and arrested him without allowing him to escape with Shasta. Her recovery ended a nationwide search that had continued for approximately seven weeks.
Information provided by Shasta became important to investigators. Duncan also began confessing to crimes following his arrest, eventually admitting responsibility not only for the Groene murders but also for earlier child killings.
Confirmed Murder Victims
- Anthony Michael Martinez, 10 - Abducted April 4, 1997, in Beaumont, California. His body was discovered April 19, 1997, in Berdoo Canyon in the Indio Hills area of Riverside County. The exact date of death was not conclusively established. Duncan later confessed and pleaded guilty to his murder.
- Brenda Groene, 40 - Murdered May 16, 2005, at her home near Wolf Lodge Bay outside Coeur d'Alene, Idaho. She suffered fatal blunt-force injuries during Duncan's attack on the household.
- Mark McKenzie, 37 - Murdered May 16, 2005, at the Groene residence near Coeur d'Alene, Idaho. McKenzie was Brenda Groene's boyfriend and was killed during the same attack.
- Slade Groene, 13 - Murdered May 16, 2005, at his family's home near Coeur d'Alene, Idaho. Slade was Brenda Groene's teenage son and the older brother of Dylan and Shasta.
- Dylan James Groene, 9 - Abducted May 16, 2005, from his family's Idaho home and murdered during his captivity in the Lolo National Forest in Montana. The exact date of his death was not publicly established; it occurred between May 16 and July 2, 2005. His remains were discovered July 4, 2005.
Confessed or Suspected Murder Victims
- Sammiejo White, 11 - Last seen alive July 6, 1996, after leaving the Crest Motel in Seattle, Washington. Her remains were discovered February 10, 1998, near Bothell, Washington. Her exact date of death was never conclusively determined. Duncan confessed to killing her, but he was never prosecuted for the murder.
- Carmen Cubias, 9 - Last seen alive with her half-sister Sammiejo White on July 6, 1996, in Seattle, Washington. Her remains were found with Sammiejo's on February 10, 1998, near Bothell. Her exact date of death was not established. Duncan confessed to killing both girls, although no murder prosecution was brought against him in Washington.
Surviving Victim
- Shasta Groene, 8 at the time - Abducted from the family residence near Coeur d'Alene, Idaho, on May 16, 2005, after Duncan murdered her mother, brother, and mother's boyfriend. She was held captive with Dylan in Montana and subjected to prolonged abuse. Shasta survived and was rescued when Duncan was recognized with her at a Coeur d'Alene restaurant on July 2, 2005.
Guilty Pleas and Sentencing
On October 16, 2006, Duncan pleaded guilty in Idaho state court to three counts of first-degree murder and three counts of first-degree kidnapping involving Brenda Groene, Mark McKenzie, and Slade Groene. He initially received three consecutive life sentences without parole for the kidnapping charges while sentencing on the murder counts was delayed as federal prosecutors pursued the case involving Dylan and Shasta.
Federal prosecutors charged Duncan with crimes arising from the kidnapping of the two younger children, the sexual abuse they endured, and Dylan's murder. On December 3, 2007, Duncan pleaded guilty to all ten federal charges against him.
In August 2008, a federal jury determined that Duncan should receive the death penalty. He was sentenced to death on three federal counts connected to Dylan's kidnapping, exploitation, and murder, along with additional life sentences for his other crimes against Dylan and Shasta.
Duncan was later transferred to California to answer for Anthony Martinez's 1997 murder. On March 15, 2011, he pleaded guilty to the murder and kidnapping. The plea ensured that he would spend the remainder of his life in prison even if his federal death sentences were ever overturned.
The Scope of Duncan's Crimes
Duncan was convicted of murdering five people: Anthony Martinez, Brenda Groene, Mark McKenzie, Slade Groene, and Dylan Groene. His confession to the murders of Sammiejo White and Carmen Cubias raised his admitted total to seven murder victims, although the Washington killings were never adjudicated in court.
Investigators around the country examined other unsolved disappearances and child murders after Duncan's arrest because of his extensive travel, lengthy history of sexual violence, and his own statements about committing crimes. Some possible connections were investigated and rejected, while others never produced enough evidence for charges. For that reason, cases beyond the five convicted murders and the two Washington murders he confessed to should not be presented as established Duncan victims without additional evidence.
Death in Federal Custody
Duncan remained under federal death sentences while incarcerated at the federal prison complex in Terre Haute, Indiana. He was diagnosed with stage IV brain cancer and died in federal custody on March 28, 2021, at the age of 58.
His death ended the possibility of carrying out the federal death sentences, but the convictions remained. The investigation that began with the horrifying discovery at the Groene home in May 2005 ultimately exposed a much longer history of predatory violence spanning Washington, California, Minnesota, Idaho, and Montana. The survival and rescue of Shasta Groene also provided investigators with crucial information that helped connect Duncan to crimes that had remained unsolved for years.
