Ventura County District Attorney Gregory Totten says a 2005 BMW sedan registered to the actress and her ex-husband, Richard Sambora, knocked down a no-parking sign and drove off on April 17 in Thousand Oaks.
Locklear was later cited for misdemeanor hit-and-run.
In a statement Wednesday, Totten said there's not enough evidence to determine who was driving.
A call to Locklear's attorney, Blair Berk, was not immediately returned Thursday.
The 48-year-old "Melrose Place" star has a previous arrest for driving under the influence of prescription drugs; she pleaded guilty last year to a lesser charge of reckless driving.