Douglas Garland's sister pointed police to her brother as suspect, jurors in triple murder trial hear

• See the latest developments from Wednesday's testimony here: 'Large amounts of blood' found in grandparents' home, officer tells Douglas Garland murder trial
• You can also follow the trial via live tweets from MeghanGrant, theCBC'sreporter in the courtroom.On mobile? You cansee thelivebloghere.

Days into an Amber Alert, Douglas Garland's sister pointed investigators to her brother as a suspect in the disappearance ofa Calgary boy and his grandparents, jurors heardat his first-degree murder trial Tuesday.

Two weeks afterNathan O'Brienand his grandparents, Alvin and Kathy Liknes,went missing from their home in June 2014, Garland was charged. No bodies have ever been found and the Crown believes they may have been burned.

Garland'ssister and his parents testified in a Calgary courtroom Tuesday as Crown witnesses on Day 2 of the trial.

"He had some business dealings with Alvin that had fallen through. As the years went on he seemed to get more bitter about it," his sister, Patti Garland, told the courtroom onTuesday.

At the time of the family's disappearancein 2014, Douglas Garland, 56, was living with his parents on their rural property just north of Calgary.

"He had approached me and said he needed to tell me that he was going to call the police. He said he believed Alvin and Allen had stolen some property from the farm," she said.

Pattiwas in a common-law relationship with Alvin Liknes's son, Allen Liknes,at the time of the trio's disappearance.

She said the last time she spoke with her brother, with whom she had an almost non-existent relationship, was Christmas in 2013.

When the Likneses and their grandson disappeared in June 2014, Patti said, she felt "not very good" when she saw coverage of the case on the news.

After police released an image of a green truck spotted on the Likneses' street around the time of the disappearance, shehad her son take a photo of the family's old green pickup truck which wasdriven almost exclusively by her brother and contacted police.

She provided a statement to investigators and gave a sample of her DNA.

'I never seen him show violence':father of accused

Garland's father, Archie Garland, also testified Tuesday that his son was upset withAlvin Liknes, because of work they'd done together on an oil and gas pump

"Alvin didn't pay Dougie some money and that didn't sit well,"said Archie Garland, 86.

Crown prosecutor Shane Parker asked Archie Garlandif he had ever used a chemical called DNA Erase in the burn barrel the family used to incinerate garbage and he said he had not.

Under cross-examination, the elder Garland agreed withdefence lawyer Kim Ross that his son was a "loner."

"I never seen him show violence to anyone," he said.

He told Ross that on the night that the Likneses and their grandson were last seen June 29, 2014 his son had dinner with his parents.

Archie Garland said he was unaware of anyone leaving the farm that night. Around 7 a.m. the next morning, he noticedhis son was taking a shower.

Archie also said it was possible that at some point in time, Alvin and KathyLiknescould have been in the green truck that was driven primarily by his son.

Following an investigation and search of the Garland farm, where the Crown now says evidence was found "all over,"DouglasGarland was arrested and charged with murder on July 15, 2014.

'I think he's an unhappy man'

Doreen Garland told jurors that her son was an "intelligent man" who read a lot of books but wouldn't discuss his problemswith her.

"He's my son, I love him," she said. "Ithink he's an unhappy man."

Doreen testified that when she brought upnews of thefamily's disappearance after watchingTV, her son told her he did not want to talk about theLikneses.

But under cross-examination,Doreentold defence lawyer Kim Ross that her son's reaction to theLiknesesbeing mentioned wasn't out of character for him.

For about a year, Douglas Garland attended medical school at the University of Alberta until he suffered what his mother believes was a breakdown and dropped out of school.

The grudge

Alvin Liknes's son Allentestified on Monday that he, Garland and his father worked together on an oil and gas pump the father/son duo had patented in 2006 and 2007.

Garland worked on wiring for the pump, but the relationship soured around 2007, and by 2010, Alvin Liknes stopped speaking to Garland, his son told jurors.

The Crown's theory is that the killings were motivated by the"petty grudge" held by Garland over the patent dispute.

Prosecutor Vicki Faulkner said in her opening statement that Garland "methodically and obsessively" researchedAlvin and Kathy Liknes.

When he learned the couple planned to move to Edmonton, Faulkner said Garland decided to act on his grudge.

The evidence

When Jennifer O'Brien arrived to pick up her son Nathan after an impromptu sleepover at her parents' home, she found an open side door and testified Monday that she saw "pools of blood" throughout the house.

Blood was found on thebeds, walls and in the kitchen.

On the first day of the trial, which is scheduled to last five weeks, jurors heard an outline of the Crown's evidence.

Forensic analysis of Garland's computer hard drive will be presented as evidence, said Faulkner, showing someone researched topics such as "how to kill without emotion," torture and autopsies.

Jurors also heard that DNA evidence from the missing family members was found on a saw and meat hooks owned by Garland, and bones and a tiny tooth were discovered in a large burn barrel on the Garland farm.

Through what Faulkner described as "dumb luck," a mapping plane that flew over the property on July 1 and 2, 2014,took photographs that show what the Crown believes to be three bodies in the grass.

60 witnesses

The trial is being presided over by Court of Queen's Bench Justice David Gates.

On Monday, the main courtroom which seats about 60 and a second overflow courtroom were both full.

Faulkner and Shane Parker, who are prosecuting the case, said they expect to call about 60 witnesses.

• Douglas Garland killed Calgary couple andgrandson over 'petty grudge,' court hears

It's unknown whether defence lawyers Kim Ross and Jim Lutz will call any evidence.

"That's a decision we'll make at the close of the Crown's case," said Ross.

The trial will hear from two police witnesses on Wednesday:one officer who was first on the scene after Jennifer O'Brien called 911, and a second who was involved in investigating the Liknes home.

• Follow the trial via live tweets from MeghanGrant, theCBC'sreporter in the courtroom.On mobile? You cansee thelivebloghere.