SAN FRANCISCO – Mr Bob Lee, the former chief technology officer (CTO) of Square who helped create Cash App, died after being attacked in San Francisco, prompting the city’s top law enforcement official to decry a “senseless act of violence”.

At the time of his death, Mr Lee was working as chief product officer at MobileCoin, a cryptocurrency start-up founded in 2017, and acted as an angel investor for companies like Tile and Figma.

The San Francisco Police Department said on its website that officers found a 43-year-old man with stab wounds after responding to a call at 2.35am, and the person later died in hospital.

Mr Lee is survived by “a loving family and collection of close friends and collaborators”, MobileCoin chief executive officer Joshua Goldbard said on Wednesday.

“Bob was made for the new world; he was the quintessential creator, leader and consummate hacker,” Mr Goldbard said. “Bob surely had an impact that will last far beyond his short time on earth.”

Mr Lee was the first CTO of Square, the start-up co-founded by Mr Jack Dorsey of Twitter fame, and now called Block. While at the company, he created Cash App, a money transfer tool that lets users buy stocks and Bitcoin. Earlier in his career, he helped develop the Android mobile operating system while working as a software engineer for Google.

Mr Lee’s work on Android and then Square made him a “mythical figure” to young tech workers beginning their careers, said Mr Max Rhodes, who joined Square in his early 20s and worked closely with him on Cash App.

“Everybody worshipped him. He could solve problems other people could not solve. All the best engineers wanted to work with him,” Mr Rhodes said.

Mr Lee would later become an investor in Mr Rhodes’ start-up, Faire.

“I don’t think I would be where I am today without him,” Mr Rhodes added.

Figma CEO Dylan Field also recalled Mr Lee’s early support of his company and wrote on Twitter: “It’s so hard to believe he’s gone.” BLOOMBERG