At knee-level on a closet door, a small bloody handprint was left behind in what appears to have been a violent struggle to get a five-year-old boy and his grandparents out of their home. DNA from the blood matched that of Nathan O'Brien, 5, and his grandmother Kathy Liknes.

Douglas Garland, 57, is being tried on three counts of first-degree murder in the deaths of the boy and his grandparents Alvin and Kathy Liknes in June 2014.

The five-year-old had been left at the home in southwest Calgary for a sleepover on June 29, 2014. When his mother arrived the next morning, all three were gone and the house was splattered with blood.

The bloody handprint had swiped downward when it came into contact with the closet door, according to Sgt. Jody Arns, a blood pattern expert with the Calgary Police Service who testified on Wednesday.

A bloody handprint with DNA from both Nathan O'Brien, 5, and his grandmother Kathy Liknes was found on a closet door about knee high from the floor. (Court exhibit )

​In several areas of the home, DNA from Nathan and Kathy was found mixed together. When Jennifer O'Brien left her son at her parents' home, the grandmother and grandson were sleeping in the same bed together.

Both Alvin and Kathy were dragged through parts of the house, Arns said.

Based on her analysis of the bloodstains, Arns said there were four areas of the home where Kathy was "positioned while actively bleeding" and three areas Alvin would have lost significant amounts of blood while stationary.

All three victims were bleeding — dripping blood and at times transferring blood onto the walls of the home — as they were forced outside.

DNA from the three victims was colour coded to demonstrate whose blood was found where in the home: purple for Kathy, blue for Alvin and green for Nathan, 5. (Court exhibit )

The blood was in various forms: drips, spatters, dried flakes, smears and pools.

Attempts appeared to have been made to clean the blood on the kitchen floor with a mop or rag, Arns told jurors.

Under cross-examination, Arns confirmed to defence lawyer Kim Ross that the victims lost "a significant amount of blood" in the incident but couldn't give a measurement as to how much or how many "impacts" each suffered.

The prosecution's theory is that the victims were taken to the Garland farm, where they were killed and their bodies burned.

An entrance near the Liknes's garage door was one of four areas in the home where Kathy was 'positioned while actively bleeding,' according to bloodstain analyst Sgt. Jody Arns. (Court exhibit)

Earlier this week, jurors were shown photos of what appeared to be the bodies of two adults and a smaller figure, laid out near three small sheds on the farm. The photos also depicted smoke coming from a burn barrel, as well as the shadow of a person standing nearby.

The images were taken by chance by an aerial-mapping plane on July 1, 2014 — the day after the three were discovered missing.

Two weeks after a massive search for Nathan and his grandparents began, Garland was arrested and charged.

Garland is connected to the Liknes family through his sister, Patti Garland, who was in a common-law relationship with Alvin Liknes's son, Allen.

Patti Garland, her parents and Allen Liknes all testified earlier that Garland harboured a grudge against Alvin Liknes after a business relationship soured years earlier.

When Jennifer O'Brien arrived at the Liknes home to pick up her son, she found blood throughout the house. (Court exhibit)

After Arns's testimony, two officers from the Calgary police surveillance unit testified about tracking Garland before he was arrested and charged with murder. They had also been asked to get a sample of his DNA.

Constables Dale Linton and Richard Massicotte said police were forced to make an arrest when Garland tried to get back onto his family's farm in the early morning hours of July 14, 2014.

Massicotte told jurors Garland ​bought a flashlight, gloves and a towel at an Airdrie Walmart about an hour before he attempted to get back onto his farm.

On Thursday, Crown prosecutors Shane Parker and Vicki Faulkner will call their final witnesses — another officer involved in the second arrest of Garland and an officer from HAWCS, the Calgary Police Service's helicopter crew.

It is expected defence lawyers Kim Ross and Jim Lutz will announce Thursday afternoon whether they will call any evidence.