A 37-year-old Spokane, Washington, resident with a previous manslaughter conviction was arrested Monday in connection with the largest of the region’s three wildfires, which have displaced thousands of people and destroyed hundreds of structures, authorities said.

Aaron Farinacci, 37, was taken into custody without incident with the help of a SWAT team after a judge signed a warrant based on an allegation of first-degree arson, Spokane County Sheriff John Nowels said at an evening news conference.

Farinacci was being held on $1 million bond, he said. It was unclear whether he has been formally charged or has a lawyer, and the Spokane County public defender’s office did not immediately respond to a request for comment Monday night.

Farinacci was arrested after police said a witness reported seeing a man near the Old Trails Fire shortly before it started around 10 a.m. Saturday, Nowels said. The witness told police the man was looking into the trees and was later seen crouching at the side of a road near some grass, before he “stood up and looked very nervous” and walked away, Nowels said.

Deputies detained Farinacci the same day about a half-mile from where the fire started and questioned him, but he was ultimately released, Nowels said. He had waterproof matches and a butane lighter, which could have been used to spark the fires, Nowels said.

On Sunday, major crimes detectives were able to link the suspect to the fire “and determined that the origin of the fire was indeed exactly where the witnesses had seen Mr. Farinacci kneeling in the grass,” Nowels said.

Farinacci was known to walk in the area before and had been questioned about “arson-related behavior” in the past, though he was never arrested or convicted for that, Spokane County Prosecuting Attorney Preston McCollam said.

Farinacci has a criminal record in Arizona, McCollam said, including a conviction for manslaughter. Public records indicate he was convicted of manslaughter in 2012 for a killing in Maricopa County in 2010.

At 3,619 acres, the Old Trails Fire is the largest of three major blazes burning in the Spokane region.

The fires have taken out an estimated 700 structures and caused the evacuations of 67,000 people in the Spokane area, federal incident commander Tom Clemo said Monday. They have collectively burned through more than 8,000 acres and were 0% contained Monday night.

Nowels said there is no evidence connecting Farinacci to the other two major blazes in the region. He is scheduled to appear in court Tuesday, McCollam said.