"We're very confident we're going to find the perpetrator that has caused the damage and that has committed this crime," Maldonado said.
The Austin Fire Department on Monday released 911 audio tapes in which callers reported flames engulfing the front of the building.
"It's huge! It's a huge fire. The entire front of the mansion is on fire," one woman caller said, explaining that flames were on the porch and headed toward the second floor.
Another man reported the mansion was "lit up in the front."
"Right now the whole front door is lit," he said. "Wow, it is crazy, man."
The fire erupted at the 152-year-old mansion shortly before 2 a.m. Sunday and severely damaged the building, even as Texas Department of Public Safety troopers guarded the premises. 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.
Investigators believe one person was on the premises and set the fire, but they haven't ruled out that more people were involved, Maldonado said.
Dog team searches will help locate possible fire accelerants inside now that all fire hot spots have been extinguished, he said. A national response team from the federal Bureau of Alcohol, Tobacco and Firearms was dispatched to Texas to collect and analyze evidence.
DPS and fire investigators refused to say Monday how an arsonist might have slipped past security guards. They would not say how many guards were in place at the time.
"Anything that deals with the security of the governor, the residence, the mansion or his family, we don't discuss numbers or how we actually go about securing the first family," said DPS Capt. Paul Schulze.
Schulze said the agency always looks at what went well and what didn't when it responds to a major incident, but he wouldn't go into detail about a possible internal investigation.
"We obviously look at our actions and evaluate them and then move forward accordingly," Schulze said. State troopers who were on duty are among the witnesses being interviewed.
He would not say whether a smaller-than-usual security staff was on site since Gov. Rick Perry and his wife Anita are not currently living in the mansion. They moved to a private home in Austin last year so the structure could undergo $10 million in renovation and maintenance, including the installation of a fire sprinkler system.
All the historic furnishings, paintings and other items had been removed from the mansion for the renovation project being done by Braun & Butler Construction.
There was no immediate financial estimate of the damage the fire inflicted or decision on whether the mansion will be repaired and restored.
The Perrys, who are in Europe on an economic development trip, are expected back in Austin on Tuesday night. They had planned to resume living in the mansion next year.
Investigators said they had no evidence that the fire was politically motivated.