Conservation officer Jeff Hanratty said the witness became suspicious when he heard a loud truck in a semi-rural area of Penticton in the early morning hours of April 16th.
The witness reported seeing two men attempting to load a deer carcass into the back of a pick-up truck.
Hanratty said the two men fled — leaving the deer behind — but not before the witness took photos of them and their truck.
"It's illegal in B.C. to hunt beyond one hour after sunset or before one hour before sunrise," Hanratty said.
"There's the issue of fair chase. These animals often don't run when they see people in the dark."
Conservation officers determined the female mule deer was pregnant with twins when it was shot.
"Those fawns would likely have been birthed in the next few weeks," Hanratty said.
"The result is three dead deer and of course that has impacts to our future population."
Conservation officers put out a plea to the public asking to help identify the truck and the two suspects.
Hanratty said officers received several tips and within two days they had identified two Penticton men as suspects.
"Hunters in general are not supportive of poaching activities, and we do get tips," he said.
"To have a witness take photographs and to be able to release those to the public, that's a first that I've seen."
The suspects are facing possible charges including hunting in closed season, hunting prohibited hours and hunting without licences.