RCMP are asking the public for tips to help crack a 25-year-old cold case involving an anonymous letter and an arson attack in Prince Rupert, B.C., that killed three generations of one family.

'I can’t imagine the horror they went through' - Staff Sgt. Garry Kerr

On Feb. 5, 1990 a fire destroyed the Brooks Bank building in Prince Rupert, killing four members of the same family, Helga Rochon, her daughters Sherri and Pauline Rochon, and Pauline’s daughter Kimberly Dumais.

"The scene was horrific," said lead investigator Staff Sgt. Garry Kerr in a statement issued by police on Thursday morning. "I still think about the moment."

The fire broke out around 5:15 a.m. PT and by the time fire crews arrived the building, which had businesses on the first floor and apartments on the second and third floors, was fully engulfed in flames.

It took crews hours to put out the blaze. When investigators were finally able to examine the damage, the bodies of the four victims were discovered huddled together on the third floor apartment of Helga Rochon.

'Small child was in mother's arms'

"I can still see them huddled together in the living room area, the small child still in her mother’s arms. I can’t imagine the horror they went through," said Kerr.

The police investigation later revealed that the fire was deliberately set, but nobody was ever arrested for the arson or the four homicides.

But police did learn that it was not the first arson attack on the building. Someone had also tried to burn the building down three months earlier.

On Thursday, Helga Rochon's surviving daughter Lorraine joined RCMP in urging the public for help.

They revealed a family member had received an anonymous letter with new details about the case four years ago.

Investigators ask anyone with information about the case - especially the author of the anonymous letter - to contact police at 1-877-543-4822 or to remain anonymous, call Crime Stoppers on 1-800-222-TIPS(8477) or online at: bccrimestoppers.com