Investigators believe the fire that severely damaged an unoccupied, century-old Shaughnessy mansion over the weekend was deliberately set.

And whether or not it will be demolished and replaced after the devastating blaze will ultimately come down to exactly how much of the 9,800-square-foot home is still standing.

“It’s a set fire. That’s what happened here,” Assistant Fire Chief Ray Bryant told reporters outside the home on Monday.

The fire gutted the inside of the $14-million mansion, starting from a stairwell in the basement, he said, though he cautioned that investigators haven’t been able to get too close because the building may be unstable.

Footage from the scene showed flames shooting through the roof as the three-alarm blaze consumed the heritage property. According to Bryant, all of the home’s staircases were destroyed and a kitchen area was badly damaged. Only the exterior of the home remains intact.

Vancouver police officers asked the public for help finding anyone who saw anything that happened to the home.

“We are doing a canvass in the area and trying to locate any witnesses,” said Sgt. Jason Robillard. “Nobody was injured. The house was vacant.”

Built in 1913, it was a home for three generations of the Thorsteinsson family, said their niece, Lynn Connell, who stopped by the property Monday.

“You think of all the many times the driveway was filled with family members coming from around the province to celebrate somebody’s birthday, 50th anniversary, something like that,” she said. “There’s a lot of history in this house—a lot of Vancouver history, really.”

After her family sold, records show the home was bought a Chinese businessman named Miaofei Pan in 2012.

It’s one of at least three mansions Pan owns in the Vancouver area, whose family lives at a different Vancouver address.

The house was listed to rent for $12,000 a month, and played host to colourful costume parties last year.

Neighbours say since then the home has been empty.

One of Pan’s other expansive homes hosted Prime Minister Justin Trudeau at a $1,500-per-person fundraiser, which was blasted by opposition MPs in 2016 as a “cash for access” event, though those involved denied that.

Pan will be in court next month in a defamation lawsuit against a journalist, who raised questions about Pan’s declared income in Canada.

Pan and his wife arrived at the site Sunday, but didn’t speak to reporters. Neither he nor his family responded to inquiries from CTV News today.

Last year, firefighters responded to at least 26 suspicious fires in vacant homes.

Shaughnessy heritage rules say that if 60 per cent of the home is burned, it can be razed and rebuilt.

But that’s a worst case scenario for the neighbours who value the history.

“It’s a real shame. A real shame,” said John Beaddie, who used to live next to the property. “These houses are one of a kind.”

A previous version of this story suggested the property was for sale in February. This was based on an inaccurate posting.