Mayor Jimmy Delshad told the Los Angeles Times and KNBC-TV Thursday that police believe the shooter fired into Ronni Chasen's passenger-side window from another vehicle and not from the street or a sidewalk.
Beverly Hills police Lt. Tony Lee said earlier that nothing had been ruled out, including a carjacking, a random attack or even a targeted hit.
A veteran publicist well-known for working tirelessly to promote her celebrity clients, Chasen 64, was shot to death in her car around 12:30 a.m. Tuesday in Beverly Hills as she drove home from a party after attending the premiere of the new Cher and Christina Aguilera movie, "Burlesque."
Delshad said detectives believe the bullets came from an SUV because of the high angle of shots fired. Police found some pieces of glass - possibly from Chasen's car window - near the shooting site, but found no bullet casings, he said.
Chasen's slaying has united the competitive community of behind-the scenes- Hollywood publicists prompting them to contribute big bucks for reward money to find her killer.
The Palm Springs International Film Festival, which Chasen worked with for many years, on Wednesday offered a $100,000 reward for information leading to the conviction of her killer. Fellow publicist Michael Levine a day earlier started a fund and hoped to raise an additional $25,000 by the end of the week.
"A very good lady, a good friend and a genius at her craft. Her death is very, very sad and mystifying," festival chairman Harold Matzner said in a statement.
Police searched Chasen's Los Angeles condo and her West Hollywood office but had little immediate insight into who might have wanted to harm her.
Neighbors reported hearing gunfire and found Chasen's car crashed into a light pole on Whittier Drive, a street of multimillion-dollar homes just south of Sunset Boulevard, and a well-used shortcut to get to her home on the Westside of Los Angeles.
Beverly Hills Police Sgt. Lincoln Hoshino said the investigation is "wide open" and the police department hasn't focused on any one specific theory of what might have happened.