AUSTIN—Interior photos of the burned Texas Governor’s Mansion released by Gov. Rick Perry’s office show scorched walls, a horribly burned ceiling and other extensive damage inside the historic landmark.

Perry’s office provided the photographs of the fire damage Tuesday. The 152-year-old mansion was unoccupied and undergoing renovations when the blaze broke out early Sunday.

In one photo, a person can be seen standing on the mansion’s severely damaged but still intact large staircase. Other photos show damage of the second-floor ceiling and a view from inside the Sam Houston bedroom.

Texas canine teams and a national arson unit continued to search for clues Tuesday to pinpoint where and how the blaze began even as state troopers guarded it in the wee hours Sunday.

Investigators have initially concluded from witnesses and video surveillance tapes the fire was set shortly before 2 a.m. Sunday, said state Fire Marshal Paul Maldonado.

Officials said they’ve spotted a person of interest in the surveillance video.

“We’re very confident we’re going to find the perpetrator that has caused the damage and that has committed this crime,” he said.

An Austin-based fire expert on Tuesday reviewed the interior photos released by Perry’s office and Associated Press photographs of the mansion’s exterior, finding what he described as “a point of interest” on the front porch.

Gerald Hurst, an Austin chemist who specializes in arson analysis and who has testified as a state and federal court witness, examined the photos at the request of The AP.

Hurst said the front porch photos revealed what he described as a considerable “V pattern” of damage extending from the floor toward the ceiling.

“The point of most interest would be right in front of the front door. If the fire started there, the probability that it’s arson as opposed to accidental would skyrocket,” Hurst said. “The front porch would be a target of opportunity for something as simple as a molotov cocktail.”

The fire caused parts of the roof to buckle and charred much of the front of the white structure and its famous Greek revival-style columns.

From the front porch, the fire could have moved up the front wall, into the ceiling and spread quickly throughout the mansion. Buildings under renovation can be an attractive target for arsonists because they typically have holes in wall and ceilings that help feed oxygen to the flames, Hurst said.

State officials have yet to assess the full impact of the damage as they wait for state and federal law enforcement agencies to conclude their arson investigation.

Perry’s office has expressed strong interest in rebuilding the landmark, which has been home to Texas governor’s from Sam Houston to George W. Bush.

In addition to a sprinkler system, the renovation project, first estimated at $10 million, was to include new plumbing, lead paint abatement and restored windows and shutters. It was to have been completed by next spring.