Murders of Nathan O'Brien, Kathryn Liknes and Alvin Liknes

On June 29, 2014, five-year-old Nathan O'Brien and his grandparents, Kathryn and Alvin Liknes, disappeared from the Likneses' Calgary, Alberta home after what police described as a "violent incident." An Amber Alert was issued for Nathan at 5:15 p.m. the following day after his mother, Jennifer, arrived at the home, found the three missing, and saw blood throughout the house. The alert became the longest in Canadian history and prompted one of the most intensive ground searches in Calgary's history, involving the Calgary Police Service, RCMP, Canada Border Services Agency, and Crime Stoppers, in an investigation named Operation Amber.

Police identified Douglas Garland, the brother-in-law of Alvin's son Allen, as a suspect after a green pickup truck seen on CCTV footage near the Liknes home was matched to a vehicle Garland drove. Garland had previously worked with Alvin and Allen on wiring for a pump and had developed a grudge related to a patent dispute with Alvin and his 2007 dismissal. A search of Garland's rural Airdrie property, conducted alongside his parents' residence, uncovered a large volume of evidence — including a Tyvek suit, restraints, torture-related items, a hacksaw, meat hooks, and burned remains including teeth and bone fragments in a firepit — over 1,400 items in total, described as the largest evidence collection for a court case in Calgary's history.

Garland was initially held on unrelated identity theft charges from the 1990s before being charged, on July 14, 2014, with two counts of first-degree murder in the deaths of the Likneses and one count of second-degree murder in the death of Nathan O'Brien; the charge for Nathan's death was later upgraded to first-degree in May 2015. Garland was arrested at his rural property in the early hours of July 14, 2014, after police used a helicopter to locate him hiding in a thicket.

Garland's trial began on January 16, 2017, and concluded on February 16, 2017, with a jury returning guilty verdicts on all three counts of first-degree murder after roughly nine hours of deliberation. The following morning, Judge David Gates sentenced Garland to a minimum of 75 years before parole eligibility, following a recommendation from 10 of the 12 jurors for consecutive minimum sentences — a term that would effectively require Garland to live to 129 years old to complete, amounting to life imprisonment in practice. Garland showed no remorse or visible emotion throughout the trial. Hours after sentencing, he was assaulted by other inmates at the Calgary Remand Centre and treated for non-life-threatening soft tissue injuries.

The case drew widespread community response, including offers to fund a possible ransom, hundreds of volunteer searchers, a green balloon tribute, a Green Ribbon campaign, a public vigil at the Alberta Legislature, and the creation of the Nathan O'Brien Children's Foundation by Nathan's parents.