Bob Lee, the financial technology executive who created Cash App and was the chief product officer of the cryptocurrency firm MobileCoin, was fatally stabbed in downtown San Francisco on Tuesday, according to the cryptocurrency platform, police and his family.

The San Francisco Police Department said late on Tuesday that a 43-year-old man was stabbed early in the day and succumbed to his injuries in hospital. The department's statement, which did not name the victim, said the incident was being investigated and that no arrests had been made.

"I just lost my best friend, my son Bob Lee when he lost his life on the street in San Francisco early Tuesday morning," said his father, Rick Lee, in a post that linked a TechCrunch article on the stabbing.

"Bobby worked harder than anyone and was the smartest person I have ever known. He will be missed by all those that knew him," he wrote.

'A force of nature'

Lee was the chief product officer for cryptocurrency company MobileCoin, where he was also previously an early-stage investor and adviser, the company said on Twitter.

"Bob was a dynamo, a force of nature. Bob was the genuine article. He was made for the world that is being born right now, he was a child of dreams, and whatever he imagined, no matter how crazy, he made real," MobileCoin CEO Joshua Goldbard wrote on Twitter.

Lee came became chief product officer at MobileCoin and helped launch the Moby app, Goldbard said.

Lee was the chief technology officer at digital payments company Square in 2013 when it launched a money transfer application now known as Cash App.

Cash App allows users to transfer money through a mobile application and is touted by the company as an alternative to traditional banking services.

Block Inc., formerly known as Square and the parent company of Cash App, was not immediately available for comment. But in a social media post Tuesday, Block CEO Jack Dorsey called Lee's death "heartbreaking" and that "Bob was instrumental to Square and Cash App."

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'A horrible tragedy': mayor

Lee was fatally stabbed in the densely populated Rincon Hill neighborhood of San Francisco, near Google's office and Oracle Park, home to the San Francisco Giants.

According to the San Francisco Chronicle, it was the city's 13th homicide of the year. 

His death further inflamed debate over public safety in San Francisco and its moribund downtown, which has not bounced back from the pandemic.

In a statement, San Francisco Mayor London Breed called the homicide "a horrible tragedy" and said that the city is prioritizing public safety.

"I'm confident that when the police make an arrest in cases like this, our district attorney will do what's necessary to hold any individuals accountable for their actions," she said.

The police statement did not provide any details on the circumstances of the stabbing. "This is an open and active investigation. For that reason we are not releasing further information," Niccole Pacchetti, a public information officer, said in an email. "We will provide further details when they become available."

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Lee remembered for impact on sector

Among the tech leaders to share their devastation about Lee's death was venture capitalist Wesley Chan, co-founder of FPV Ventures.

Chan said he befriended Lee more than a decade ago when they both worked at Google, at a time when software engineers like Lee were helping to build the Android smartphone operating system before its 2008 release.

"He was an incredibly iconic founder in the tech world," Chan said by phone Wednesday. "His resume reads something like a Fortune cover article."

But Chan said Lee was also generous in helping to coach and champion other engineers and tech entrepreneurs who'd call on him for advice.

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