Koopmans blinked rapidly but otherwise showed no emotion as his verdict was delivered following a day and a half of jury deliberations that capped an eight-week trial in B.C. Supreme Court in Penticton.
The 51-year-old was charged with the first-degree murders of Robert Keith Wharton, 43, and Rosemary Fox, 32, who died in a March 2013 triple shooting near Princeton, B.C. He was also convicted of the attempted murder of the lone survivor, Bradley Martin, 50.
"Nothing is going to bring Keith back, but it might make it easier knowing (Koopmans) is convicted of the murders," said Leesa Moldowan, who was in the courtroom for the verdict and is Wharton's former common-law wife and the mother of one of his children.
No other members of the victims' families were present, but Moldowan said she spoke to them by phone and they were pleased with the outcome.
"I'm just glad this part of it is over for the family so they can get some closure," she added.
Crown counsel Frank Dubenski said afterwards the issue of Koopmans' intoxication by alcohol on the night in question was likely one with which jurors struggled and that he believes ultimately led to their finding of second-degree murder, which doesn't require the element of premeditation.
"I'm quite satisfied that it's the right verdict," said Dubenski.
Defence counsel Don Skogstad said Koopmans found solace in the fact he "may have some life left" by the time he's released from prison.
Skogstad said he will now discuss with his client the possibility of an appeal.
Koopmans is due back in court April 27 to fix a date for sentencing.
He faces a mandatory minimum sentence of at least 10 years in prison before he's eligible for parole on each murder conviction, and the judge is not bound by the recommendation of the jury, a female member of which wiped away tears as the verdict was read.
The star witness at trial was Martin, who testified Koopmans shot him after he tried to intervene in an argument between Koopmans and Wharton regarding a break-in at Koopmans' home.
Martin fled the Wharton residence on Old Hedley Road after he suffered a single bullet wound to his chest, but was able to finger Koopmans as the shooter.
Wharton's mother, who also lived on the property, soon after found Fox and her son lying dead in their bed after receiving a total of five gunshots to their heads.
Koopmans denied involvement, despite being arrested in a camper on the property the day after the shootings and being found with Wharton's DNA in blood spatter on his pants.
He testified that he saw police at the property and, suspecting a drug bust was underway, went to sleep in the camper following a drunken argument with his girlfriend, and that the blood spatter was sneezed there 10 days earlier by a dog who licked up Wharton's blood after Wharton was injured while sorting lumber.
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