Bob Lee, the founder of Cash App, a multibillion-dollar payment app, was fatally stabbed near San Francisco city centre on Tuesday. Lee was also the ex-chief technology officer at Square. San Francisco officials have faced criticism for their handling of a surge in violent crime in recent years. The city’s latest crime data suggests it is one of the most dangerous in the US. Lee’s death has prompted renewed calls for action on violent crime. Lee was living in Miami, Florida, but was in San Francisco for a leadership summit and to see friends. At the time of his death, Lee was the chief product officer of cryptocurrency company MobileCoin. No suspects have been identified in the ongoing investigation.