Nearly two months after a fatal stabbing sent shock waves through downtown Petaluma, police arrested a 25-year-old Napa man in connection with the homicide.

Police arrested Bryan Webster at his home in Napa on Nov. 2 on suspicion of murdering Cristian Nunez-Castro, 24, of Windsor in the Golden Concourse on Kentucky Street Sept. 10.

“We developed some leads over the past few weeks through viewing surveillance videos and interviewing people,” Petaluma Police Lt. Tim Lyons said. “We were able to develop some concrete leads that led us to the suspect.”

Officers from the Petaluma and Napa police departments and the Rohnert Park Department of Public Safety assisted with a search of the Napa home and the arrest, Lyons said. Officers also searched a residence in Cotati where police believed they might find evidence, Lyons said.

He declined to provide details about evidence retrieved during the searches, but said officers are currently evaluating its merit.

Lyons said he doesn’t believe Webster has a criminal history. He was unable to provide details about his occupation.

Police have no indication that Webster and Nunez-Castro knew each other prior to the stabbing, and a clear motive has not yet emerged, he said.

“We just know there was some type of altercation, and we’re trying to find out what that was and why it started,” he said.

Webster is being held without bail at the Sonoma County Jail on charges of murder and assault with a deadly weapon, according to the jail’s booking log.

Lyons said police are now following up on additional leads, conducting interviews and processing evidence.

“We still have to investigate ... Only one person committed the stabbing but there were other people involved,” he said, declining to elaborate.

Lyons hopes the arrest will assuage mounting fears after the unusual early morning violence erupted in the central business district.

“People downtown will feel better knowing that a suspect has been arrested ... people were anxious about it,” he said.

(Contact Hannah Beausang at hannah.beausang@arguscourier.com)