SAN FRANCISCO (AP) The murder trial of a tech consultant in the stabbing death of Cash App founder Bob Lee begins Monday, a year and a half after the widely admired entrepreneur was found staggering on a deserted downtown San Francisco street seeking help.

Lees death at age 43 stunned the tech community , and fellow executives and engineers penned tributes to his generosity and brilliance. Lee was chief product officer of cryptocurrency platform MobileCoin when he died. He was a father to two children.

Prosecutors say Nima Momeni, 40, planned the April 4 attack after a dispute over his younger sister, Khazar, with whom Lee was friends. They say Momeni took a knife from his sisters condo, drove Lee to a secluded area and stabbed him three times, then fled.

Defense lawyers disagree , and they say that Lee, high on drugs , attacked Momeni.

Our theory is that Bob had the knife, and that Nima acted in self defense, attorney Saam Zangeneh said.

He said his client is eager to tell his side of the story, but they havent decided whether Momeni will testify in his defense.