SAN FRANCISCO — Nine days after the fatal late-night stabbing of Bob Lee set off a furious outcry over public safety in San Francisco, law enforcement officials said on Thursday that they had arrested an acquaintance of the prominent tech executive and would charge him with murder.
The police identified the man accused in the killing as Nima Momeni, 38, a tech entrepreneur and consultant whom family members said Mr. Lee had known personally.
The owner of an enterprise tech business in the East Bay city of Emeryville, Mr. Momeni was taken into custody there after an intense investigation that played out against heated claims that the killing reflected a city where the professional class was vulnerable to random attacks. Mr. Momeni was booked on Thursday morning into the San Francisco County Jail and is scheduled to be arraigned on a murder charge on Friday.
At a news conference, law enforcement officials acknowledged growing concerns about random violence and property crimes in the city but insisted that Mr. Lee’s killing did not fit that pattern.
“This has nothing to do with San Francisco — it has to do with human nature,” Bill Scott, the city’s police chief, said.
Scott Wiener, a Democratic state senator who represents the city, said the rush to judgment by tech luminaries such as Elon Musk and colleagues of Mr. Lee, a well-known figure in the Silicon Valley, was both inaccurate and damaging to San Francisco, which has been straining to rebound from the coronavirus pandemic.
“This is the danger of making one crime into a symbol,” Mr. Wiener said. “This was a horrific, brutal murder, and I am so grateful that the police solved it so quickly. And San Francisco does have real public safety problems. But this particular crime does not appear to have anything to do with them.”
Mr. Lee’s brother, Oliver Lee, of Palo Alto, Calif., said in an interview on Thursday that the moves to “co-opt” the tragedy had been agonizing for his family. “Bob loved being in San Francisco, and San Francisco loved Bob,” he said, adding that young people would stop his brother on the street there and ask for advice.
He said that his brother, a father of two who had recently relocated to Miami after spending most of his career in the Bay Area and Silicon Valley, had left the city for work reasons and had returned there often, both for business and to spend time with his teenage daughters, who continued to live in the Bay Area with his former wife.
Brooke Jenkins, the San Francisco district attorney, said that “the loss of a young, vibrant leader and innovator has rocked our city and even beyond.” But she criticized what she said were “reckless and irresponsible statements” portraying the city as a hotbed of violent crime, pointing to comments by Mr. Musk, the chief executive of Twitter and Tesla, in particular.
Rates of violent crime have dipped or held steady over the past several years in the city of about 808,000 people. National crime data showed that the city’s murder rate in 2020 was low compared to that of other major American cities.
Nonetheless, the killing has continued to generate waves of recriminations and heightened tensions between the city and the tech sector that is so critical to the city’s economic fate.
Jason Calacanis, a tech investor and entrepreneur, tweeted on Thursday that “anyone who walks a couple of blocks in San Francisco (outside of Pac Whites where things seem to be oddly safe) knows how dangerous the city is,” using slang to refer to the affluent Pacific Heights neighborhood.
The arrest, which was first reported by Mission Local on Thursday morning, capped days of speculation around the death of Mr. Lee, 43, a tech executive who was found bleeding by emergency medical workers at about 2:35 a.m. on April 4 on a sidewalk. The authorities and family members said he had been in San Francisco on business at the time of the assault.
Police officials declined to discuss details of the case or the motive, and Mr. Lee’s brother said that his family was not well acquainted with the suspect, whom he portrayed as one among many tech entrepreneurs in his brother’s orbit.
“From what we’ve learned recently, it seems like it was more like entrepreneurs and people trying to make their name in San Francisco,” Oliver Lee said. But he added that the family did not share his brother’s closer acquaintance with Mr. Momeni or know why the two might have met on the night the killing occurred.
Mr. Momeni’s LinkedIn profile states that he owns a tech support company called Expand IT Inc., which is housed in a loft-like brick space in Emeryville, across the bay from San Francisco. According to his business card, his business focuses on the management of computer servers, cybersecurity and general I.T. support.
Alameda County court records show that Mr. Momeni was charged in 2011 with illegal possession of a switchblade and driving with a license that had been suspended because of a past conviction for driving while intoxicated. He pleaded no contest to the suspended license charge, and the knife charge was dismissed.
The charges being filed this week against Mr. Momeni include a penalty enhancement for murder committed with a knife.
Sam Singer, a Bay Area public relations executive who is Mr. Momeni’s neighbor in the century-old steam-engine factory that has been converted into offices, described Mr. Momeni as a good neighbor, calling him “bright, hard-charging, charming.” Mr. Momeni’s office space was “a classic San Francisco Bay Area tech office” with a pool table, a high-end stereo system and gourmet food in the kitchen, Mr. Singer said.
Emptied of office workers during the pandemic, downtown San Francisco has experienced an increase in tent encampments and open-air drug use in its public spaces, fueling complaints that the city’s compassion for homeless and mentally ill people has complicated its ability to maintain order. Property crimes have risen, and enough voters felt unsafe that they ousted the local prosecutor, Chesa Boudin, last year.
In the emotional aftermath of the killing, high-profile figures including Mr. Musk and Michael Arrington, the founder of the industry blog TechCrunch, blamed the city for Mr. Lee’s death.
San Francisco recorded 56 homicides in 2017, but some violent crimes dipped early in the pandemic. In 2021 and 2022, the homicide count was back up to 56, according to data from the city’s Police Department. Before Mr. Lee’s death, the city had recorded a dozen killings this year, two more than in the same period the year before.
However, the high-profile crimes have continued to highlight the city’s problems. Days after Mr. Lee was killed, for instance, a former fire commissioner was attacked with a metal pipe in the Marina District and left hospitalized; the victim’s family blamed an encampment of homeless people that he had sought to force out of the upscale neighborhood. In March, the San Francisco Board of Supervisors approved a request from Mayor London Breed to spend an additional $25 million on police overtime.
Mr. Lee was known by his friends and relatives as a kind, brilliant man and a generous mentor, but also as a prodigiously energetic and social person, with an ability to stay out late even on weeknights. His online handle was Crazy Bob, a nickname he had earned while playing water polo in his youth.
He had risen to prominence first as the chief technology officer of the payment company Square — which changed its name to Block in 2021 — and then at MobileCoin, a cryptocurrency start-up based in San Francisco, where he was chief product officer at the time of his death. Colleagues said Mr. Lee also had been instrumental in creating the mobile payment service Cash App.
HIs brother, who called the loss “crushing,” described him as an idealist who dreamed of democratizing technology and who loved art and music. Bob Lee’s friendships were vast, Oliver Lee said, from the venture capital offices of Silicon Valley to the regular crowds at the annual art and music festival Burning Man. The brother said he had been told that Mr. Lee had visited a friend earlier on the night of his death. “Bob,” he said, “would make time for anyone.”
Similar to the attack in the Marina District, the stabbing of Mr. Lee occurred in an upscale part of the city known as Rincon Hill. A quiet neighborhood that is popular with tech workers, the area is near downtown and not far from Google’s office and the stadium that is home to the San Francisco Giants, Oracle Park.
The neighborhood is a tech hub, and it caters by day to tech workers and other professionals with pour-over coffee shops, grab-and-go lunch counters and a specialty grocery store. But the streets tend to empty after dark as residents retreat into skyscraper condominiums.
Before moving to Miami — Mr. Lee told friends that he liked the energy of the city’s tech start-ups — he lived in Mill Valley, an affluent community about 15 miles north of San Francisco in Marin County. Mr. Lee recently had shared a home with his father, according to his father’s social media posts.
“Life has been an adventure with two bachelors living together, and I’m so happy that we were able to become so close these last years,” the father, Rick Lee, posted on Facebook. “Bob would give you the shirt off his back. He would never look down on anyone and adhered to a strict no-judgment philosophy.”
Kalley Huang, Tim Arango and Kate Conger contributed reporting. Susan C. Beachy contributed research.