A Gilroy resident who investigators believe has ties to the militant, far-right "Boogaloo" movement was arrested last week for allegedly sending more than 20 threatening and profane letters to Santa Clara County Health Officer Dr. Sara Cody.

The Santa Clara County Sheriff's Office announced Tuesday that it had arrested 55-year-old Alan Viarengo on charges of stalking and threatening a public official, and found an arsenal of weapons, ammunition and explosives at his home. Detectives zeroed in on Viarengo after they positively identified his fingerprints on numerous threatening and profane letters that were sent to Cody and then watched him drop off another letter addressed to Cody with similar threatening messages.

Detectives also found Viarengo's fingerprint on a letter that had been sent to the widow of Sgt. Damon Gutzwiller, a deputy in the Santa Cruz County Sheriff's Office who was fatally shot on June 6 while responding to a report of a suspicious vehicle in Boulder Creek, according to a news release from the Santa Clara County Sheriff's Office. The letter mocked the death of Gutzwiller and wished death upon more law enforcement officers.

Detectives believe Viarengo had sent a total of 24 letters to Cody. These letters became "increasingly aggressive, offensive and threatening," according to the news release. They requested a warrant from the District Attorney's Office for Viarengo's arrest for felony stalking and threatening a public official.

According to the news release, Viarengo's letters suggested that he is a member of the loosely organized "Boogaloo" movement. Its members, conspicuous for wearing tactical gear and Hawaiian shirts during demonstrations, are known for anti-government and pro-gun views.

Viarengo was arrested on Aug. 27 at his home in Gilroy, according to the news release. Detectives also found 138 firearms, thousands of rounds of ammunition and explosive material at his home.

He was arraigned on Monday and scheduled for a plea hearing Tuesday afternoon, according to online Santa Clara County Superior Court records.

Anyone with information about this case is asked to call the Sheriff's Office at 408-808-4500 or the Investigative Services anonymous tip line at 408-808-4431.

Cody, who holds a central role in Bay Area's response to the COVID-19 pandemic, is one of a growing roster of public health professionals to face threats since March, when the onset of the pandemic prompted them to issue shelter-in-place orders. Dr. Anthony Fauci, director of the National Institute of Allergy and Diseases and the nation's leading infectious disease officer, told CNN last month that he had received death threats. As this news organization has previously reported, numerous county health officers in California have abruptly resigned during the pandemic due to stress, threats or other reasons.

In Santa Clara County, the sheriff's office initiated a 24-hour security detail to protect Cody after she began receiving irate and profane letters, according to the news release. Made up of deputies, sergeants and detectives, the security detail was responsible for collecting, vetting, processing and documenting any threatening correspondence to Cody.

The county's Department of Public Health said in a July statement that while the public health officer's decisions have saved thousands of lives during the pandemic, they have "placed a spotlight that has made our public health officer the target of serious threats from a few individuals."

"We condemn any effort to harm or intimidate our public health officer, an individual who deserves our respect and appreciation for having the bravery to make the tough calls needed to protect the health and wellbeing of all our residents, including the most vulnerable members of our community," the county's announcement stated.

Palo Alto Weekly Staff Writer Sue Dremann contributed to this report.