Joseph Duncan dies of brain cancer on death row 16 years after slaughtering family


Nearly 16 years after murdering three young boys and a North Idaho family, a convicted child molester and killer has died of brain cancer while on death row.

Joseph E. Duncan died early Saturday at a hospital in Terra Haute, Indiana near the federal prison he was serving his sentence on federal death row, KXLY reported.   

He was sentenced to death in 2007 for the Idaho murder of nine-year-old Dylan Groene, his brother Slade Groene, 13, his mother Brenda Groene, 40 and her fiance Mark McKenzie, 37. In 2011, he admitted murdering another young boy, ten-year-old Anthony Martinez.

Duncan’s attorneys disclosed late last year that he had terminal brain cancer and did not have long to live. He lost the final appeal of his death sentence in 2019.

‘The sun is a little brighter today,’ said Diana Martinez, Anthony’s mother. ‘My soul is lighter. The world is a more beautiful place without the evil that is Joseph Duncan. God chose to make his end a long suffering and I believe that is fitting. The horror of his thoughts consumed him.’  

Duncan was arrested following the brutal murders of the Groene family in May 2005.

The killer had broken into their Coeur d’Alene, Idaho, home, and kidnapped the two youngest; eight-year-old Shasta Groene and nine-year-old Dylan, before bludgeoning Brenda, Slade and Mark to death. 

Serial killer Joseph Duncan in a police photo published in 2011. Duncan's attorneys disclosed late last year that he had terminal brain cancer

Joseph E. Duncan, pictured in a police booking photo, died Saturday of brain cancer in an Indiana hospital while serving a sentence on death row for several murders

Joseph E. Duncan, pictured in a police booking photo in 2008, right, and in 2011, left, died Saturday of brain cancer in an Indiana hospital while serving a sentence on death row for several murders

Anthony Martinez of Beaumont, California, was murdered by Joseph Duncan in April 1997

Dylan Groene in an undated photo provided by police. He was killed by Joseph Duncan after he and his sister, Shasta, were kidnapped from their home in Idaho in 2005

VICTIMS: Anthony Martinez of Beaumont, California, (left) was murdered by Joseph Duncan in April 1997, Dylan Groene (right) was killed in 2005

Duncan held the children captive for weeks in a cabin in Montana, molesting and then killing Dylan before returning Shasta to a Denny’s restaurant in Coeur d’Alene.

After his arrest, DNA evidence linked him to the April 1997 killing of Martinez of Beaumont, California.

Martinez was killed while Duncan was on parole for a rape charge in Washington. He was kidnapped while playing outside of his home and his body was found 15 days later.

Duncan was not suspected of the crime until after his arrest in Idaho and he was extradited to Southern California to be tried for the crime.

Brenda Groene, pictured in an undated photo, was killed along with her son, Slade Groene, and her boyfriend, Mark McKenzie, by child molester Joseph Duncan

Brenda Groene, pictured in an undated photo, was killed along with her son, Slade Groene, and her boyfriend, Mark McKenzie, by child molester Joseph Duncan

Steve Groene, left, with his daughter, 8-year-old Shasta Groene, in July 2005 in Coeur d' Alene, Idaho

Steve Groene, left, with his daughter, 8-year-old Shasta Groene, in July 2005 in Coeur d’ Alene, Idaho

Flowers were left at a memorial service for Dylan Groene in July 2005 in Post Falls, Idaho

Items were left by community members near the home of Dylan and Shasta Groene outside Coeur d' Alene, Idaho, in July 25. The children were kidnapped from the house where Joseph Duncan killed the other members of their family

Flowers were left at a memorial service for Dylan Groene in July 2005 in Post Falls, Idaho

An undated evidence photo shows the cabin in Montana where Joseph Duncan held Dylan and Shasta Groene and filmed his crimes

An undated evidence photo shows the cabin in Montana where Joseph Duncan held Dylan and Shasta Groene and filmed his crimes

Slade Groene, murdered by serial killer Joseph Duncan in 2005, is remembered by his father in a Facebook post on March 29 with the caption: 'Happy 27th Birthday Slade. You are so loved and very missed'

Mark McKenzie, seen in an undated Kootenai County Sheriff Department photo, was killed along with members of the Groene family by Joseph Duncan

Slade Groene (left) and Mark McKenzie (right) were murdered by serial killer Joseph Duncan in 2005

Duncan was also linked to the killings of two young girls in Seattle in the 1990s. 

In 2005, Duncan was accused of molesting a young boy on a playground in Minnesota. He posted a low bail and skipped town. 

Duncan was driving to Washington, where his family lived, when he said he spotted the Groene children playing outside their home along Interstate 90.

He planned to kidnap the children, buying night vision goggles and stalking the family.

Duncan videotaped many of his crimes against the Groene children, leading a veteran investigator to say the footage shook him to his core.  

‘While I would’ve liked to witness his execution, knowing he is now standing before God being held accountable for what he has done, what he did to my son, and the horrible crimes he committed to others, that is the real justice,’ Anthony Martinez’s father, Ernesto, said.

Anthony’s younger brother, Marcos, said there is now ‘less evil in the world.’

‘Nothing can bring my brother back, but now Duncan can never hurt anyone again. Because of him, I will spend the rest of my life doing everything I can to fight against any evil left in the world,’ Marcos Martinez said.

‘God has brought pure justice for all those Joseph Duncan has hurt,’ he said. 

Leave a Reply