Santa Clara County Sheriff’s Office By LUKE BARR and IVAN PEREIRA, ABC News

(SANTA CLARA, Calif.) — Authorities in California charged an alleged member of the far-right extremist “boogaloo movement” Tuesday with threatening a public official after investigators say he sent threatening letters to a county health officer.

The Santa Clara Sheriff’s office said it had been investigating letters sent over the last several months to Dr. Sara Cody, the Santa Clara County public health officer, that used “profane and threatening language” against her, the sheriff’s office said in a news release.

The 24 letters allegedly had indicia of the “boogaloo movement,” according to the police.

Investigators discovered a fingerprint on one of the letters and matched it with Alan Viarengo, 55, of Gilroy, the sheriff’s office said.

Officers set up surveillance of Viarengo and saw him drop off a letter at a post office mailbox in Watsonville, the sheriff’s office said. Investigators worked with the United States Postal Service and intercepted the letter, which was allegedly addressed to Cody and contained a threatening message, officials said.

Detectives obtained a search warrant for Viarengo’s home and arrested him on Aug. 27 after finding a cache of weapons, said the sheriff’s office.

“After conducting a search of Viarengo’s residence, detectives located 138 firearms, thousands of rounds of ammunition, and explosive materials,” the sheriff’s office said in its news release.

Investigators also said Viarengo’s fingerprint was found on a threatening letter sent to the widow of Santa Cruz County Sheriff’s Office Sgt. Damon Gutzwiller, who was killed in the line of duty on June 6 by an alleged boogaloo follower.

“The letter contained language mocking the death of Sgt. Gutzwiller and also wishing death upon more law enforcement officers,” the sheriff’s office said.

Attorney information for Viarengo, who was charged with stalking and threatening a public official, was not immediately available.

The boogaloo movement, whose name is coined from a term used by extremists to signify a civil war, is known for its anti-government, anti-police and pro-gun beliefs. The group has been linked to several attacks and attempted attacks against police and government officials.

The movement has also allegedly infiltrated Black Lives Matter protests to incite violence, according to investigators.

“We’re seeing actions from boogaloo followers where they’re targeting police and other government officials and serve as real concerns for law enforcement,” said former Department of Homeland Security acting undersecretary and ABC News contributor John Cohen. “Notwithstanding what the administration puts out each and every day, the threat facing the United States comes not only from far left-wing extremists but from those on the far right, including those who seek to incite a second Civil War.”

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