Prosecutors in Santa Clara County have served at least three search warrants while investigating whether Sheriff Laurie Smith’s office gave out coveted concealed-gun permits in exchange for campaign money, sources familiar with the investigation told The Chronicle.

The Santa Clara County district attorney’s office raided the sheriff’s San Jose headquarters Aug. 2, seizing evidence through a search warrant that remains sealed. About a week before that, sources said, prosecutors served search warrants on two of the sheriff’s higher-ranking supervisors.

Among those who have been contacted by investigators is AS Solution, a security company whose bodyguards protect Silicon Valley tech executives. Public records show one of the company’s managers gave a large contribution last year to an independent expenditure committee supporting Smith’s re-election.

The sources, who are people familiar with details of the investigation, spoke on the condition they not be identified and in accordance with The Chronicle’s policy on using such sources. The probe was first made public by the website San Jose Inside.

The sheriff did not respond to requests for comment. A personal attorney for Smith, who was voted into office in 1998, said she has never exchanged campaign contributions for gun permits.

“It’s absurd this is an issue given the stinginess in which the sheriff gives out” the permits, said the attorney, Rich Robinson.

Prosecutors are investigating the Sheriff’s Office at a time when demand for specialized security is high among Silicon Valley companies and executives, particularly since April 2018, when a disgruntled YouTube video creator stormed the company’s San Bruno headquarters and shot three people before taking her own life.

Many private guards are retired police officers who may carry hidden guns in California. Those who are not retired officers must apply for permits from their home city or county. The permits generally must be renewed after two years.

It is unclear how many of those licenses have been granted in Santa Clara County, where officials have denied The Chronicle’s requests for information about issued permits, citing the investigation. They also said such a disclosure would not serve the public’s interest.

The ease of obtaining concealed weapon licenses can vary widely by county. San Francisco’s sheriff has no active licenses, the sheriff in Alameda County currently has granted more than 250, and Solano County has more than 2,300.

A century-old state law requires successful applicants to complete a training course, be of “good moral character” and show “good cause” for why they need a concealed weapon. But county and city law enforcement agencies have broad discretion in determining who meets those criteria, according to a 2017 state audit of the program.

The auditor found no “bad effect” from the discretion allowed in issuing concealed carry permits, but each county examined in the report — Los Angeles, San Diego and Sacramento — often failed to follow its own policies and guidelines. Some policymakers, including Assemblyman Kevin McCarty, D-Sacramento, have argued that the licensing process should be more uniform and strict.

Santa Clara County District Attorney Jeff Rosen’s office issued a brief written statement saying that warrants served on the Sheriff’s Office helped retrieve “certain items” as part of an “ongoing investigation.”

Deputy Michael Low, a Sheriff’s Office spokesman, said in a statement that the agency is “fully cooperating” with prosecutors.

A spokesman for AS Solution, a Bellevue, Wash., security company that employs more than 600 people across the globe and specializes in executive protection, including work for leaders at Facebook, Google and other Silicon Valley corporations, told The Chronicle the company is cooperating with the probe.

AS Solution would not comment on the substance of the investigation or whether it is related to a large contribution that a company manager made in October to an independent committee that supported Smith’s 2018 re-election. Public records show that the $45,000 check came from a manager who has no record of previous political contributions in the county. The manager did not respond to requests for comment.

Christopher Schumb, a San Jose attorney who acted as co-treasurer for the committee that received the check, the Santa Clara County Public Safety Alliance, declined to comment.

In response to questions from The Chronicle, AS Solution released a statement saying it is “cooperating fully with the Santa Clara County district attorney’s office, and we have launched our own internal investigation into this matter.”

“AS Solution employees are required to obey the laws, rules and regulations of all countries where we conduct business, and any allegations of improper conduct by employees are treated very seriously,” the statement said. “We will take appropriate action based on the outcome of our investigation.”

Because of Santa Clara County’s refusal to provide documentation on applicants for concealed-gun licenses, it is unknown how many AS Solution employees, if any, received them in that county. Possession of a concealed-gun permit is a requirement for some jobs at AS Solution, according to the company’s online job listings.

Executive protection is a priority at many tech firms, particularly those with famous leaders. For example, Securities and Exchange Commission filings show that Facebook spent $9.9 million in the last fiscal year on security for CEO Mark Zuckerberg.

A Facebook spokesman said AS Solution has been one of its security contractors since 2011 and that the company “is one of several security firms we use globally to provide security services for Mark and other key executives.”

A spokesman for Google said AS Solution “is one of our many contractors.”

In 2017, the Ninth U.S. Circuit Court of Appeals ruled that carrying a concealed gun is not a Second Amendment right and that California sheriffs and police chiefs should have discretion in awarding concealed-weapons permits. During the court fight, agencies were flooded with applications, and the Santa Clara County Sheriff’s Office noted at the time it was working through a backlog.

Past recipients in the Bay Area have included CEOs, security guards, merchants who deal in cash or jewelry, public figures such as professional athletes, and judges, prosecutors and others who have been threatened, records show.

Christian West, chief executive of AS Solution, said on the company’s website in July 2018 that obtaining a concealed-gun permit in California is “considered to be practically impossible for most people in certain counties.” In the same post, West wrote that demand was rising for executive security, citing mass shootings and “perceived threats of terrorism.” The YouTube shooting, he said, “shoved the topic to the center of attention in Silicon Valley, which is known for a lot of things, but not a pro-gun culture.”

The debate over the tight permit controls has taken on special intensity in Santa Clara County. In 2011, a security manager for a semiconductor company sued Smith with support from gun-rights groups, saying he had been unfairly denied a permit three years earlier. Tom Scocca dropped the suit in a 2016 settlement in which Smith promised to consider future permit applications from him. It is unclear whether he ever obtained the permit.

The Chronicle compared campaign contribution records with an older list of Santa Clara County gun-permit holders and found the names of more than two dozen people who have supported Smith’s personal campaign committees or the Public Safety Alliance committee. The list of permit holders, obtained from a confidential source, was not comprehensive and did not include the date each permit was issued.

The contributions, between $100 and $8,000, were made over the past decade and went to either Smith’s personal campaign or the Public Safety Alliance, the independent expenditure committee. The committee raised $95,000 in 2018 and spent $67,500 supporting Smith’s candidacy, campaign disclosure forms show.

Among the Smith backers who have received concealed-gun permits are the heads of tech firms and investment companies and private investigators. Some were frequent contributors in local elections, but at least 11 appeared to have made no other political contributions in Santa Clara County over the past decade. It is unclear whether any of these contributions are being examined by investigators.

Josh Koehn Matthias Gafni and Joaquin Palomino are San Francisco Chronicle staff writers. Email: josh.koehn@sfchronicle.com, matthias.gafni@sfchronicle.com, jpalomino@sfchronicle.com Twitter: @Josh_Koehn, @mgafni, @JoaquinPalomino