Joseph Edward Duncan III (February 25, 1963 – March 28, 2021) was an American convicted serial killer and child molester who was on death row in federal prison following the 2005 kidnappings and murders of members of the Groene family of Coeur d'Alene, Idaho. He was also serving 11 consecutive sentences of life without parole for the 1997 murder of Anthony Martinez of Beaumont, California. Additionally, he confessed to—but had not been charged with—the 1996 murder of two girls, Sammiejo White and Carmen Cubias, in Seattle, Washington. At the time of the attack on the Groene family, Duncan was on the run from a child molestation charge in Minnesota.
During his incarceration, authorities connected Duncan with the unsolved murders of Anthony Martinez in California and two girls in Seattle, which all occurred when Duncan was on parole from 1994 to 1997. In all, he was convicted in Idaho for kidnapping and murdering the three victims in Coeur d'Alene, for which he was given six life sentences: in federal court for kidnapping Shasta and Dylan Groene and murdering Dylan, for which he was given three death sentences and three life sentences; and in the state of California for kidnapping and murdering Martinez, for which he was given two life sentences.
Duncan died on March 28, 2021, at the age of 58, as a result of a terminal brain tumor.
Early life and criminal history
Joseph Edward Duncan III was born at Fort Bragg, in North Carolina, on February 25, 1963. He was the fourth of five children born to Joseph Edward Duncan Jr and Lillian Mae Duncan. He had three older sisters and a younger brother. His father was in the United States Army. Because of this, the family moved from city to city within the U.S. and abroad, changing locations every year or two until the elder Duncan retired to Tacoma, Washington when the younger was around 12 years old. His mother was described as a domineering woman. After being arrested in 1980, he claimed to have been abused as a child; however, his younger brother disputed this. His parents split up in 1979 and divorced in 1983. His sisters soon left the household all at once, and he remained behind with his mother while his brother went to live with their father after some time. His father would later remarry, giving Duncan a stepfamily. He attended Lakes High School but did not graduate.
Duncan had a long history as a violent sexual predator. He committed his first recorded sex crime in 1978 when he was 15 years old. In that incident, he raped a 9-year-old boy at gunpoint. The following year, he was arrested for driving a stolen car. He was sentenced as a juvenile and sent to the Jessie Dyslin Boys Ranch in Tacoma, where, according to a report by the Associated Press, he told a therapist assigned to his case that he had bound and sexually assaulted six boys. He also told the therapist that he estimated that he had raped 13 younger boys by the time he was aged 16.
In 1980, Duncan stole several guns from a neighbor and abducted a 14-year-old boy, raping him at gunpoint. He was sentenced to 20 years in prison for this crime but was released on parole in 1994 after serving 14 years. While out on parole, Duncan is known to have lived in several places in the Seattle area. He was arrested again in 1996—this time for marijuana use—and released on parole several weeks later with new restrictions. Authorities believe that he murdered Sammiejo White and Carmen Cubias in Seattle in 1996 and Anthony Martinez in Riverside County, California, in 1997, during his parole period; however, both those cases went cold and were not tied to him until after his arrest in the Groene case. He was arrested in Missouri and returned to prison in 1997 after violating the terms of his parole; he was released from prison on July 14, 2000, with time off for good behavior and moved to Fargo, North Dakota.
In March 2005, Duncan was charged with the July 3, 2004, molestation of two boys at a playground in Detroit Lakes, Minnesota. On April 5, 2005, he appeared before a Becker County judge, who set bail at US$15,000. A Fargo businessman, with whom he had become acquainted, helped him post bail. However, he skipped bail and disappeared. On June 1, a federal warrant was issued for his arrest for the "unlawful flight to avoid prosecution."
On May 16, 2005, authorities discovered the bodies of Brenda Groene, 40; her boyfriend, Mark McKenzie, 37; and her son, Slade Groene, 13, in their home along Lake Coeur d'Alene, outside the city of Coeur d'Alene, Idaho. Two of Brenda's other children–Dylan, 9, and Shasta, 8–were missing. An Amber alert was issued and searchers combed the area for the missing children while authorities investigated the deaths at the home as homicides. Autopsies determined the cause of death to be "blunt trauma to the head"; authorities also noted that the victims had been bound.
Forty-seven days later, in the early morning of July 2, 2005, Shasta was seen at a Denny's restaurant in Coeur d'Alene in the company of an unknown man. A waitress, a manager, and two customers there recognized the girl from media reports. They surreptitiously called the police and positioned themselves to prevent the man from leaving. Police officers arrived at the restaurant and arrested the man, later identified as Duncan, without incident. Shasta identified herself to the waitress at the restaurant and authorities, and was taken to Kootenai Medical Center for medical treatment and to be reunited with her father. Coeur d'Alene police, meanwhile, detained Duncan on kidnapping charges and on his outstanding federal warrant.
When Shasta was found without Dylan, authorities held little hope of finding the boy alive. Police asked the public for tips, specifically concerning sightings of the stolen red Jeep Cherokee with Missouri license plates that Duncan was driving at the time of his arrest. Authorities discovered that Duncan had rented the car in Minnesota and never returned it. A gas station employee in Kellogg, Idaho, about 40 miles (64 km) east of Coeur d'Alene, recognized the vehicle as one that had stopped at her station hours before Duncan was arrested. The employee suspected the girl wandering around the station might have been Shasta but did not confront her as nothing appeared out of the ordinary. The employee and her manager notified authorities after reviewing surveillance camera footage and identifying Duncan and Shasta in the video.
On July 4, 2005, investigators found human remains at a remote, makeshift campsite in the Lolo National Forest near St. Regis, Montana. The remains were sent for DNA testing to the FBI lab in Quantico, Virginia, where they were positively identified as Dylan's. During the trial, it emerged that Duncan shot him at point-blank range by holding a sawn-off 12-gauge shotgun to his head.
Much of what is known about the murders of the Groene family was revealed by Shasta Groene herself. According to Shasta's police interview, Duncan killed her mother, older brother, and her mother's fiancé. Then, he kidnapped her and her brother, driving away with them in the stolen Jeep Cherokee.
Shasta told investigators her mother came into Dylan's and her room and woke them up. Her mother said, "Someone is in the house," and led them into the living room, where Shasta saw Duncan wearing black gloves and holding a gun. Duncan tied her mother's hands with nylon zip ties and did the same to her mother's fiancé and Shasta’s brother Slade. Duncan removed Shasta and Dylan from the house and placed them outside on the lawn. While waiting outside with her brother, Shasta heard multiple thumping sounds during the time that Duncan bludgeoned the three people remaining inside the home to death. She then saw her injured older brother, Slade, staggering away from the entrance to the house. Once he had finished murdering the three inside, Duncan placed Shasta and Dylan in his car. He took both children to other locations, where he repeatedly raped and tortured them for six weeks. Shasta stated that they drove a long distance and stayed in two different campsites, during which time Duncan told her of having beaten her family members to death with a hammer.