Kirby faces up to 18 years in prison.
Kirby pleaded not guilty to the charges, including vehicular manslaughter and driving under the influence causing bodily injury.
Orange County Deputy District Attorney Jason Baez told jurors that Jeffrey Kirby caused the crash that killed Charles Lewis Jr., the 45-year-old known in the mixed martial arts world as "Mask," the founder of the Tapout clothing line.
"This case is about two drivers driving at extremely high, extremely unsafe speeds," said Baez.
Kirby was driving a 1977 Porsche and Lewis was driving a 2004 Ferrari on Jamboree Rd. in Newport Beach on March 11, 2009.
"The Porsche's speed is in a range that's above 100 mph," said Baez.
Baez alleges the Kirby, 53, lost control of his car and hit Lewis's Ferrari, sending him crashing into a concrete light pole. The impact split the Ferrari in two. Lewis's passenger survived after being thrown from the vehicle. Lewis was killed instantly.
Baez said Kirby, who has a prior conviction for driving under the influence, was drinking the night of the crash.
"Mr. Kirby had previous warnings that driving under the influence kills," said Baez. "He chose to drink, chose to drive, chose to speed."
Baez said Kirby then fled the scene, parking his car around the corner from the crash.
The defense says Kirby did not run, but cooperated with police.
"He didn't know for several hours that that that Ferrari had crashed," said defense attorney Mark Fredrick.
Fredrick blames Lewis for the crash, insisting Kirby lost control and spun out when Lewis tried to zip past him at a frighteningly fast speed.
"Mr. Kirby made a quick movement to try to get out of the way of that Ferrari coming up from behind him," said Fredrick.
Baez said Lewis was speeding, but he would not have lost control and crashed if it weren't for Kirby.