Ten months after Jaycee Dugard was snatched off a South Lake Tahoe street in 1991, a caller told police he thought he had just seen the girl at an Oakley gas station, staring for a long time at a picture of herself on a "missing" poster, authorities told The Chronicle on Monday.

The call came from a pay telephone at a Chevron station that is less than 2 miles from the home outside Antioch where police now say Dugard was held for 18 years in a backyard compound of sheds and tents by Phillip Craig Garrido and his wife, Nancy Garrido.

The man who called in the tip to the Contra Costa County Sheriff's Office reported seeing the girl return to a yellow van, possibly a Dodge, authorities said Monday. Last month, police towed away a dilapidated, yellow Dodge Ram van with flat tires that was half-buried in dirt behind the home of Dugard's kidnap suspects.

Sheriff's Capt. Dan Terry confirmed the possible early sighting of Dugard after being asked about it Monday by The Chronicle.

Terry said such tips are common in criminal cases that are highly publicized, as Dugard's kidnapping was in the early 1990s. He said his agency had responded appropriately, sending a deputy to the gas station, but that the yellow van was gone, as was the caller - who did not leave his name and has never come forward.

"We don't know if there was any truth to it," said Terry, who is head of investigations for his agency. "We don't know if it was real or a hoax. Nothing ever came of it."

Terry said the call was made about 6 p.m. on April 22, 1992, almost a year after Dugard was abducted on June 10, 1991, while she waited alone on a South Lake Tahoe street for a school bus. She was 11 when she was kidnapped and is now 29.

Police had no license plate to track and no good location to stake out, Terry said, and the caller did not say which direction the van had driven. He said dispatchers would have alerted other officers to be on the lookout for the van, and that a copy of the report had been sent to investigators in El Dorado County, who were leading the search for Dugard.

The Sheriff's Office searched for Dugard's name in a database after she was found in late August and unearthed the old incident report, Terry said.

The Garridos have pleaded not guilty to charges that they kidnapped and raped Dugard. She had two of Phillip Garrido's children and eventually helped him run a printing business, authorities said.

After Dugard was found, Contra Costa County Sheriff Warren Rupf apologized for an incident in which a deputy had missed a potential opportunity in 2006 to spot Dugard.

A neighbor of the Garridos told authorities that "little girls and women" appeared to be living in the backyard, but the deputy left after delivering only a warning about potential code violations, Rupf said.

The Chevron station, located on a rural stretch of road near Highway 4, was owned in 1992 by Jimmy Bean of Antioch. His wife, Jane Shearrer, said Monday that her husband was out of town and could not be reached. She said she had no recollection of the station being connected to a possible sighting of Dugard.

McGregor Scott, a Sacramento attorney who is acting as a spokesman for Dugard and her family, declined to comment on the possible sighting. A spokesman for the El Dorado County Sheriff's Office did not return a call.