The fourth week of the Garland triple murder trial is underway and a Calgary police officer who scoured hours of surveillance footage was the first to testify on Monday.

Douglas Garland, 57, is charged with three counts of first-degree murder in the deaths of Alvin and Kathy Liknes and their grandson Nathan O’Brien.

** WARNING - GRAPHIC DETAILS FOLLOW **

On Monday, court heard from Cst. Gerald Bouchard, an investigator with the Calgary police Homicide Unit, who said he looked into suspicious activity around the Liknes home, between 10:00 p.m. on June 29 to 10:00 a.m. the next day.

Bouchard said he waded through a great deal of footage and a green pickup truck, which was captured on a neighbour’s surveillance camera, caught his attention.

He said he tracked the truck and figured out where it came from and where it went.

Bouchard told the court that he gathered video from businesses and other locations and compared it to other traffic to make sure they were watching the right truck.

He said that the truck was captured on video twice at the same location at different times and that the second time it was recorded, there was an object covered by a white tarp in the truck bed.

Bouchard testified that the truck was seen heading northbound out of the city and it was then spotted going southbound on the QEII Highway at 7:21 a.m. The pickup turned into the Liknes' neighbourhood at 7:47 a.m.

Peregrine, an aerial photography company, that did some mapping for the City of Airdrie, took photos of the Garland property on July 1 and 2, 2014.

At the beginning of the trial, Crown prosecutor Vicki Faulkner said the photos were taken just a few days after the disappearance of the victims and some of them showed the bodies on the farm.

The mapping aircraft is equipped with expensive cameras and the Crown says the images were captured by ‘dumb luck’.

Paul Gagnon, from Peregrine, told the court that pilots follow a grid pattern when they fly to ensure complete coverage. He says an image is taken every three seconds and that it also captures GPS data.

The court was shown photos of the property and what appeared to be two bodies lying face-down in the grass and a third figure curled up nearby.

The photo was taken at 9:23 a.m. on July 1, 2014. Another photo of the same area was taken the next day and the figures do not appear to be in it.

Gagnon says he became aware of the contents of the images in April 2015.

Douglas Garland was in court on Monday and studied the images on a monitor in front of him during the proceedings.

The trial has wrapped for the day and is expected to last another two weeks.

@CTVInaSidhu is covering the trial for CTV Calgary.