ANTIOCH, Calif. —  Police say a woman kidnapped 18 years ago in Northern California has so far not offered any clues in two other child abductions in the 1980s.

Police in Hayward and Dublin are trying to determine if the couple charged with kidnapping Jaycee Dugard in 1991 are linked to the disappearances of two girls in the cities.

They have been searching Phillip and Nancy Garrido's backyard in Antioch this week for clues.

Hayward police Lt. Chris Orrey said Friday they have not talked to Dugard directly but have had other law enforcement agencies ask her questions on their behalf.

The Garridos have pleaded not guilty to kidnapping and raping Dugard.