Bear wasn't tagged - GPS SOS signal is likely how they were alerted. That being said, if they found an aggressive bear in the area, I'd be inclined to trust them. There isn't really anything to gain by lying, especially if it leads to another hiker death from the actual bear.

Parks Canada received an alert indicating a bear attack from a GPS device in the Red Deer River Valley around 8 p.m. Friday. A grizzly bear displaying aggressive behaviour was found in the area and was euthanized by Parks Canada for public safety reasons. First aid kits and knowledge, bear spray and a GPS are all important tools in case of an attack, Titchener said.