Who Were Joseph Duncan’s Victims? How Many Did He Kill? How Did He Die?

Joseph Duncan Death

Joseph Duncan Death: Who was Joseph Dunca? Who Were His Victims? How Did He Die? – Duncan’s heinous crime spree came to a stop in July 2005, when he was apprehended at a café in Coeur d’Alene, Idaho. He had murdered a family and kidnapped two children in the same city. ‘People Magazine Investigates: Groene Family Massacre,’ a documentary on Investigation Discovery, focuses on Joseph’s actions and the other young children he murdered.

So, if you’re interested in knowing about Joseph Dunca death, his victim lists, and his life, keep reading below.

Must Read: Where Are Anthony Martinez’s Mother and Brother Today?
who was Joseph Edward Duncan
Joseph Edward Duncan III

Who was Joseph Edward Duncan?

Joseph Edward Duncan III (February 25, 1963 – March 28, 2021) was an American serial killer and child molester who was sentenced to death in federal prison for the kidnapping and murder of members of the Groene family of Coeur d’Alene, Idaho, in 2005. In addition, he was serving 11 life sentences without the possibility of parole for the same murders, as well as the 1997 murder of Anthony Martinez of Beaumont, California.

Duncan also confessed to the 1996 murders of two Seattle girls, Sammiejo White and Carmen Cubias, for which he had not been charged. In addition, Duncan was on the run from a child molestation charge in Minnesota at the time of the attack on the Groenes.

Duncan has a criminal record extending back to the age of 15 when he was growing up in Tacoma, Washington. He had spent all but eight years of his adult life in prison after being sentenced to 20 years in prison for sexually assaulting a youngster in Tacoma in 1980. In 1994, he was released on parole, but in 1997, he was sent to prison for breaking the terms of his release.

Brenda Groene, her boyfriend, and her 13-year-old son were discovered dead in the family home near Coeur d’Alene in Kootenai County, Idaho, in May 2005. Groene’s two other children, Shasta, eight, and Dylan, nine, were also reported missing by authorities. Shasta was found alive with Duncan at a restaurant in Coeur d’Alene nearly seven weeks later, after an intensive search for the two youngsters.

Duncan was jailed in connection with her kidnapping. When Shasta recovered, she told the authorities that Duncan had told her that he was returning her to her father because he had changed his mind about killing her. Duncan claimed that she taught him how to love, she claimed. Dylan’s body was discovered in a rural area outside St. Regis, Montana, a few days later. Duncan was charged with the murders of Dylan and the three other victims at the Coeur d’Alene residence.

During Duncan’s sentence, investigators linked him to the unsolved deaths of Anthony Martinez in California and two females in Seattle, all of which occurred between 1994 and 1997, when he was on parole. Duncan was only charged with one of the deaths, in California. Duncan received six life sentences in Idaho for kidnapping and murdering the three victims in Coeur d’Alene; three death sentences and three life sentences in federal court for kidnapping Shasta and Dylan Groene and murdering Dylan; and two life sentences in California for kidnapping and murdering Martinez.

Duncan was diagnosed with a fatal brain tumour in March 2021, according to reports. According to court documents, he had brain surgery in October 2020 after being diagnosed with glioblastoma, a type of stage IV brain cancer. Neither chemotherapy nor radiation treatments was offered to him. Medical professionals at the Federal Bureau of Prisons believed he had six to twelve months to live in November 2020. At the age of 58, he died on March 28, 2021.

Mark McKenzie and Brenda Groene
Mark McKenzie, 37 and Brenda Groene, 40

Who Were the Victims of Joseph Duncan? How many people did he murder?

Authorities were called to a rural farm near Coeur d’Alene on May 16, 2005, to locate three bodies. Brenda Groene, 40, was found slain alongside her lover, Mark McKenzie, 37, and her son, Slade, 13 years old. They were bludgeoned to death with a hammer after being restrained with duct tape and zip ties. Brenda’s other two children, 9-year-old Dylan, and 8-year-old Shasta, were missing at the time.

Slade and Dylan Groene
Slade Groene, 13 and Dylan Groene, 9

Dylan Groene and Slade

The intense hunt for the children lasted weeks before Shasta was discovered with an older man at a café on July 2, 2005. He was identified as Joseph Duncan, the man who had murdered Shasta’s family and abducted her with her brother only a few days before. The tiny child remembered everything that had transpired and informed the authorities, offering important information. Joseph took the kids to a remote campsite in Montana’s Lolo National Park after they were kidnapped from their house.

Shasta claims she was threatened and sexually abused while she was there. Joseph abused, threatened, and abused the two children before shooting Dylan in the head with a shotgun. He then wrapped the small boy’s body in a tarp and set fire to it. Later, he recruited Shasta’s assistance in transporting her brother’s ashes to a river and disposing of them in a pipe. There were films about Joseph abusing children.

Martinez, Anthony

When Joseph was arrested, according to the little girl, he was taking her back to the family. His lengthy criminal history was quickly discovered by the authorities. While residing in Tacoma, Washington, in 1980, Joseph, then 16 years old, stole firearms and ammo from a neighbor. Then he kidnapped a 14-year-old boy and sexually molested him. Joseph was sentenced to 20 years in prison for this, of which he served 14 years before being released on parole. After violating his parole requirements, he was sentenced to three further years in prison. In the year 2000, Joseph relocated to Fargo, North Dakota.

Joseph enrolled at a university there, but he was charged with another sex offence in 2004. He was accused of sexually assaulting a 6-year-old boy at a Minnesota playground in 2004. Joseph was released on bail, but he fled the area without informing the authorities. He was eventually discovered in Idaho. Authorities also discovered a blog that was thought to have been written by Joseph. Joseph claimed in it that he was not a paedophile because he had been molested as a child numerous times and felt it was normal.

Carmen Cubias and Sammiejo White
Sammiejo White and Carmen Cubias

Sammiejo White and Carmen Cubias

Joseph also discussed exacting vengeance on society for imprisoning him. “My objective is to hurt civilization as much as I can, then die,” he continued. Joseph planned to kidnap children in Montana before heading to Idaho, according to officials. The GPS in the automobile he was driving gave him several waypoints in several states, all of which had children. Joseph saw Shasta and Dylan playing outside their house, scouted the area for a few days, and then kidnapped them.

Joseph confessed to killing three additional people while in detention. Carmen Cubias, 9, and Sammiejo White, 11, resided with their mother in a motel in Seattle, Washington, in 1996. They went out to a local restaurant one night but never returned. Moreover a year and a half later, their skeleton remains were discovered. Joseph claimed he abducted them off the street and beat them with a crowbar in the head.

He kidnapped 10-year-old Anthony Martinez off a street in Riverside County, California, in early April 1997 and beat him in the head with a rock. Two weeks later, his body was discovered under some stones in Berdoo Canyon, California.

Shasta and Dylan Groene
Shasta (left) and Dylan Groene (right).

Complete List of Joseph Duncan’s Victims

When and where the victims were discovered are indicated by the dates and places.

  • Unnamed nine-year-old child, unspecified day in 1978, Tacoma, Washington (raped at gunpoint, but not killed).
  • An unnamed 14-year-old boy in Tacoma, Washington, on an unspecified date in 1980. (abducted, raped, and sodomised at gunpoint; was released).
  • Anthony Michael Martinez, 10 years old, died on April 19, 1997 in Indio, California (abducted on April 2 in Beaumont, California; molested and killed, allegedly by bludgeoning with a rock).
  • On July 3, 2004, in Detroit Lakes, Minnesota, a six-year-old kid went missing (molested only).
  • Unnamed friend of the boy (attempted to molest).

Idaho: The Groene family Murder (May 16, 2005)

  • Brenda Groene is a 40-year-old woman.
  • Brenda Groene’s boyfriend, Mark McKenzie, 37
  • Brenda Groene’s oldest son, Slade Groene, is 13 years old.

The Double Abduction

  • Dylan Groene, 9 (Brenda Groene’s youngest son; repeatedly raped, abused, and tortured; fatally shot and burned post-mortem; his body was discovered on July 4) was abducted.
  • Shasta Groene, 8 (Brenda Groene’s daughter; raped and molested numerous times before being rescued on July 2)
Joseph Duncan Death
At the age of 58, he died of brain cancer on March 28, 2021, at a hospital in Indiana.

Joseph Duncan’s Death: How Did He Die?

Joseph pleaded guilty to the murders of Brenda, Slade, and Mark in 2006. Then, the next year, he pled guilty to kidnapping, sexually abusing, and murdering Dylan and Shasta. In 2011, Joseph acknowledged killing Anthony in court and was sentenced to life in prison without the chance of release in California. What happened in Idaho and then across state borders resulted in Joseph being sentenced to death three times over, as well as earning multiple life sentences.

Joseph was diagnosed with stage IV brain cancer while on death row and underwent surgery in 2020. Later, he turned down chemotherapy and radiation treatments. Joseph’s disease had progressed to the point where a specialist projected he wouldn’t live for more than a year in November 2020. At the age of 58, he died in the early hours of March 28, 2021, at a hospital in Indiana.

Watch ‘People Magazine Investigates: Groene Family Massacre’ episode on Investigation Discovery.