SAN FRANCISCO — A GPS tracker placed a California arson suspect’s vehicle at the scene of a destructive wildfire north of San Francisco last month about a minute before it started, according to an investigation of the suspect in the blaze that destroyed 189 homes.

Investigators first placed a tracker on Damin Pashilk’s vehicle in August 2015 after a series of small arson fires over the previous weeks that Pashilk is also accused of starting. Videotaped surveillance had placed a car Pashilk drove near at least some of those fires, according to a summary of the California Department of Forestry and Fire Protection’s investigation of Pashilk that was obtained by The Associated Press.

Pashilk pleaded not guilty in a Lake County courtroom on Wednesday to 18 counts of arson related to 16 fires, including the August 13 blaze that damaged the town of Lower Lake. His attorney, J. David Markham, declined to comment, saying he wanted to first finish reviewing hundreds of pages of documents that had been turned over to him by authorities.

The investigation summary shows authorities tracked Pashilk’s whereabouts using a GPS device and direct surveillance by investigators. Pashilk was observed taking photos of one fire he is accused of starting in August 2015, according to the summary.

On August 7, 2016, an investigator tracking Pashilk noticed he had stopped along a state highway. The investigator found a fire burning in the brush minutes after Pashilk left, according to the summary.

Two days later, an investigator spotted another fire near where Pashilk’s vehicle had also stopped minutes before.

The GPS tracker showed Pashilk had slowed down to 11 miles per hour at the site of the August 13 fire about a minute before it started, according to the summary. He was arrested two days later.

State fire spokesman Daniel Berlant said investigators didn’t have enough evidence against Pashilk to present a “solid case” to prosecutors until after the Aug. 13 fire.

He declined to say whether that blaze yielded additional evidence against Pashilk beyond the GPS tracking and surveillance in the investigation summary.

“The arrest was made as soon as we had enough evidence that we believed provided a solid case that we could turn over to the DA’s office,” he said.