Andrew Thomas Gallo also pleaded not guilty through his attorney to three other felony charges and one misdemeanor in connection with the April 9 collision that occurred just hours after Adenhart pitched six scoreless innings in his season debut.
The 22-year-old Gallo watched from inside a security enclosure as defense attorney Randall Longwith entered the pleas before an Orange County Superior Court judge. About 15 members of Gallo's family were in court.
While waiting for Gallo to appear, 24-year-old Jon Wilhite, the lone member of Adenhart's group to survive, began to sob. Wilhite, who had critical injuries in the wreck, was embraced by friends and family.
Longwith said later in an interview that he will seek a change of venue because he believes Gallo cannot get a fair trial in Orange County, home of the Angels and the California State University, Fullerton, baseball team for which Wilhite had played.
The attorney noted that in another courthouse where Gallo made a previous appearance, an Angels poster was in the hallway leading to the courtroom.
Longwith also said there have been death threats against Gallo and himself via the Internet, phone and in a letter.
"I think people are venting and it's just evidence of the passion people have in this case. I don't think it's a true threat," he said, noting he had not brought it to the district attorney's attention.
Deputy District Attorney Susan Price disputed the need for moving the case.
"We don't believe that the defendant will be any more prejudiced in this county than in any other county," said Price, who was flanked by the victims' family members at a brief news conference outside the courtroom.
All the families declined to comment after the hearing. Some family members wore T-shirts and large buttons emblazoned with photos of their children.
Price said Gallo faces a mandatory minimum sentence of 45 years to life in prison if convicted of the three second-degree murder charges. If convicted of all charges, the minimum would be 54 years and eight months to life.
Police have said Gallo had nearly triple the legal blood-alcohol level when the minivan he was driving ran a red light in Fullerton and broadsided the silver Mitsubishi Eclipse carrying Adenhart and three friends to a dance club to celebrate his success.
The impact spun around both vehicles, and one then struck another car but that driver was not hurt, police said.
Gallo fled on foot and was captured about 30 minutes later, police said.
The 22-year-old Adenhart died in surgery at the University of California, Irvine Medical Center. Another passenger, 25-year-old Henry Nigel Pearson of Manhattan Beach, and the driver, 20-year-old Courtney Frances Stewart of Diamond Bar, died at the scene.
Stewart was a student at nearby Cal State Fullerton, where she was a cheerleader in 2007-08. Pearson, who played high school baseball with Wilhite, was a graduate of Arizona State University and was pursuing a law degree when he died.
Wilhite, of Manhattan Beach, was hospitalized for weeks for "internal decapitation," a rare and often fatal separation of the skull from the spinal column.
Wilhite, who played baseball from 2004-08 at Fullerton, has since been discharged from the hospital and is undergoing outpatient physical therapy.
He came to the arraignment in a wheelchair but was able to get up and enter the courtroom under his own power, albeit with an unsteady gait. His head was closely shaved and had a long scar at the base of the skull.
He and his family declined to comment after the arraignment.
Longwith noted that Gallo was being housed in a 14-man jail cell and was not in protective custody. He said his client is frequently in tears during their meetings and was crying when he came into court.
"He was pretty much in shock," Longwith said.
(This version CORRECTS spelling of Wilhite's first name to Jon sted John in 4th graf.)
Copyright 2009 The Associated Press.