Bob Lee, 43, of Mill Valley, was found wounded around 2:30 a.m. on the 400 block of Main Street, police said. Police later issued a statement saying they initially responded to the 300 block of Main St. on the report of a stabbing.
Officers called medics and attempted to keep him alive, but he was rushed to the hospital where he died.
His father, Rick Lee, shared on Facebook that he just lost his best friend. He said he moved to Mill Valley with his son in 2019 when his mother died, and they had recently relocated to Miami.
"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," Lee wrote. "Bob would give you the shirt off his back. He would never look down on anyone and adhered to a strict no-judgment philosophy."
Flowers were placed at the spot where paramedics and police found Lee. Many stopped by Wednesday to pay tribute and reflect on a person they said made valuable contributions to the community.
"It's a tragic situation," neighbor Karan Shaw said. "Paying our respects is the least we can do."
Investigators have not publicly named any suspects and no arrests have been made, worrying people in the Rincon Hill neighborhood.
"For someone who contributed so much, who was a founder and creator, I'm really upset," neighbor Yasmin Hariri said. "I don't feel safe."
San Francisco Supervisor Matt Dorsey, who represents the area, said he has heard the calls to curb crime and admitted work needs to be done.
"This is a senseless tragedy and obviously it’s made worse by the knowledge that there’s no suspect in custody," he said. "If you know something or are aware of something, say something."
The tech community shared messages of shock as they learned about Lee's passing.
"It's real. Getting calls. Heartbreaking," said Jack Dorsey, Founder at Square. "Bob was instrumental to Square and Cash App. STL guy."
"Bob was a dad, the former CTO of Square where he created Cash App & CTO of Mobile Coin. He was a generous decent human being who didn’t deserve to be killed," tweeted Bill Barhydt, CEO of Abra.
"Saying Bob’s name in the past tense feels ridiculous," wrote Joshua Goldbard, founder of Mobilecoin. "I don’t even know where to begin."
"RIP @crazybob - you were generous to me and so many others, an important part of tech and you brought infectious energy everywhere." wrote Josh McFarland of Greylock. "For your kids and family, I hope justice prevails here."
Police ask the public to help them find who is responsible for the deadly stabbing. They ask anyone who has cell phone video or video from a parked car between 2:10 a.m. - 2:35 a.m. to please contact San Francisco police.
"I want to assure everyone that our investigators are working tirelessly to make an arrest and bring justice to Mr. Lee and his loved ones, just as we try to do on every homicide that occurs in our city," SFPD Chief Bill Scott said in a statement issued Wednesday night.
Scott said the investigation is in its early stages and would not comment on evidence nor would police speculate on the circumstances of the crime.
District Attorney Brooke Jenkins tells KTVU she will hold anyone who commits these types of violent crimes to account. She also expressed condolences to the Lee family.
"I am devastated for them," Jenkins said. "As the top law enforcement officer in this city and county, I will ensure that if somebody is arrested for this crime, that we prosecute them to the fullest extent of the law."
A tip line is available at 415-575-4444 or text a tip to TIP411 and begin the text message with SFPD.
KTVU's Brooks Jarosz contributed to this report. E-mail him at firstname.lastname@example.org