Mark Zuckerberg addresses the 'Facebook killer' tragedy: 'We have a lot more to do here'

Facebook's biggest conference of the year kicked off in San Jose, California on Tuesday with a presentation by CEO Mark Zuckerberg.

Early in his talk, Zuckerberg addressed the big Facebook news story of the moment: Steve Stephens, who was the subject of a nationwide manhunt after he posted a Facebook video showing him killing an elderly man.

Even politicians like Pennsylvania Governor Tom Wolf have called Stephens the "Facebook killer." Police said Stephens killed himself on Tuesday.

"We have a lot more to do here," Zuckerberg said. "We're reminded of this this week by the tragedy in Cleveland. Our hearts go out to the family and friends of Robert Godwin Sr., and we have a lot more work and we will keep doing all we can to prevent tragedies like this from happening."

After a pause, Zuckerberg returned to discussing Facebook technologies and products.

Watch Facebook's F8 presentation below: