Tech exec Bob Lee, 43, who created the mobile payment service Cash App was stabbed to death in San Francisco, California Tuesday morning, according to several media reports and the San Francisco police.

Lee, who served as the chief product officer of San Francisco-based cryptocurrency company MobileCoin since Nov. 2021, previously worked at Google where he led Android’s core library team and launched the world’s most-used operating system.

He then joined Square — the payment company that later became Block — to develop the Android app and later became the company’s first Chief Technology Officer.

Lee, also known as ‘Crazy Bob’, was an investor in tech startups including SpaceX, Clubhouse, Tile, Figma, Faire, Orchid, Addressable, Nana, Ticket Fairy, Gowalla, Asha, SiPhox, Netswitch, and Found, according to TechCrunch.