Alice Gruppioni, 32, was on her honeymoon when she was hit by the blue Dodge Avenger, which is reported to have been going at up to 90km/h, on Saturday. Eleven others were injured in the rampage.
Campbell, from Colorado, pleaded not guilty during a hearing in Los Angeles on Tuesday and is due back in court on September 4th.
Witnesses said Campbell, who is reported to have a criminal record for reckless driving while under the influence of alcohol, looked as if he was driving “with a purpose”. He later turned himself in at a police station in Santa Monica.
He is reported to have said: “I do not know why I did it. It’s not clear if I was drunk or on drugs,” according to La Stampa.
The body of Alice, who is the daughter of Bologna football club’s former president, Valerio Gruppioni, is being flown back to Italy on Wednesday. Her funeral is taking place in her home town of Pianoro, near Bologna, on Thursday.
Alice was a manager at the family firm, Sira Group, which makes heating radiators.
She married Christian Casadei on July 20th. They arrived in Los Angeles following a trip that took them to Las Vegas, the Grand Canyon and Monument Valley.
“We were walking, we were happy, on honeymoon, and suddenly everything changed. I still can’t believe it and do not remember exactly what happened,” Casadei is reported to have said earlier this week.