Los Angeles police spokesman Kevin Maiberger said Friday that a video recording shows Tobias Summers crossing over a pedestrian bridge into the Mexican city of Tecate at a point just east of San Diego. Police have declined to reveal exactly when the video was made.
The girl vanished from her Northridge home in the early morning hours of March 27. She was found about 12 hours later wandering near a Starbucks several miles away.
Summers, 30, is charged with kidnapping, burglary and nearly three dozen counts of sexual assault.
He's described as a transient with a criminal record including convictions for burglary and grand theft.
The commander of Mexico's Baja California state police fugitive squad told the Los Angeles Times that Mexican authorities are in daily contact with Los Angeles police.
"We're thinking that he did cross the border and he is on our side of the fence, but we don't know exactly where," said Cmdr. Alfredo Arenas.
Mexican authorities have distributed "wanted" posters with Summers' picture and have put police in the cities of Tecate, Ensenada and Rosarito Beach on alert.
An alleged accomplice in the girl's abduction is in custody.
Daniel Martinez, 29, has pleaded not guilty to kidnapping and burglary.
Authorities believe Summers broke into the girl's home planning to burglarize it but instead abducted her at knifepoint. They believe Martinez was waiting outside in a car the two used to flee with the girl.
Martinez soon abandoned the car and vanished, police have said, while Summers took the girl to a vacant home where he assaulted her.
Summers has a criminal record dating to 2002 that includes arrests for robbery, battery and grand theft auto. Court records show Martinez has been convicted of burglary and grand theft.