Detectives believe they drove through Rancho Cucamonga on or around October 9.
New surveillance video was released Thursday as the search for a missing 9-year-old Santa Barbara County girl intensifies.
The sheriff's office shared a short clip of Melodee Buzzard and her mom, Ashlee Buzzard, at a rental car agency on October 7.
According to authorities, the mother allegedly switched license plates during a road trip that took them through Southern California in an apparent effort to avoid detection.
Detectives believe that Ashlee Buzzard also may have changed her appearance during her travels, changing into a darker wig that is similar in color and style to the one Melodee is seen wearing in the video.
On Oct. 7, the mother and daughter left on a three-day road trip from Lompoc to the Nebraska area, the sheriff's office said.
The last verified sighting of Melodee is now determined to be Oct. 9, sheriff's spokesperson Raquel Zick told ABC News earlier this week.
Surveillance video shows Melodee with her mom that day near the Colorado-Utah border, Zick said. The next day, on Oct. 10, Ashlee Buzzard came home to Lompoc with the white 2024 Chevrolet Malibu she rented on Oct. 7 — but Melodee was not with her, the sheriff's office said.
Zick said investigators are now focused on the timeline from Oct. 9 to Oct. 10.
Authorities said they believe Ashlee Buzzard drove through Green River, Utah; Panguitch, Utah; northwest Arizona; Primm, Nevada; and Rancho Cucamonga.
During the road trip, the mother allegedly removed the Malibu's California license plate, number 9MNG101, Zick said. On Oct. 8, the Malibu had New York license plate number HCG9677. It's not clear when that plate was put on or if other plates were added at other times, according to the sheriff's office.
The original California plate was back on the car when Ashlee Buzzard returned it to the rental agency in California, Zick said.
It appears "the license plate was switched to avoid detection … don't have any other plausible reason," Zick said.
Ashlee Buzzard has not cooperated with the investigation, authorities said.
Melodee is still considered a missing person, Zick said. No arrests have been made.
ABC News contributed to this report.
