Shantina Smiley and 8-Year-Old Son Missing, Van Abandoned (PICTURES)

OLYMPIA, Wash. (CBS/AP) Shantina Smiley was "beyond lost" on a trip to her stepfather's house when she and her 8-year-old son Azriel Carver wound up on the backroads of Washington state, authorities said Monday.

PICTURES: Shantina Smiley and Son Missing

The minivan driven by Smiley was found partially submerged on a private Puget Sound beach with its doors open. A wallet containing the 29-year-old's driver's license, cash and credit cards was found in the van, but not Shantina or her son.

"Apparently she got stuck and abandoned the car," said Lt. Chris Mealy of the Thurston County Sheriff's Office. There was no indication, he said, that a crime took place inside the 2005 Dodge Caravan.

PICTURES: Shantina Smiley and Son Missing

Divers searched the water off the beach on Monday while bloodhounds on loan to the sheriff's office scoured the nearby roadside.

Detectives have traced Smiley's path from her home in Silverdale to the far reaches of Thurston County, more than 50 miles north of her stepfather's house in Castle Rock in Cowlitz County and far from any road that would have led her there.

Mealy said Smiley had called her fiance Saturday night in Olympia to update him on her location because she had left her cell phone at home. An employee at an Olympia diner where she bought a corn dog told investigators she left without her purchase and then tripped and fell walking back to her van, but Mealy said the fall was not serious.

PICTURES: Shantina Smiley and Son Missing

The elderly couple who lived nearby said they let Smiley use their phone to call her grandfather, gave her son a piece of pizza, and then directed her back to the freeway. She wasn't heard from again.

"The homeowners said she acted nervous because she was lost," Mealy said. She was not injured but spoke of an accident, which investigators believe may have been a reference to falling down at the diner.

Mealy said that as she left the home, Smiley made another series of driving errors that eventually led her to a hard-to-find dirt path and driving onto the beach.

"It gets dark up there. It gets really, really dark," Mealy said. "I was there Sunday afternoon. I had trouble finding that trail in the daylight."

Friends and family described Smiley as a responsible, mature woman. She has no history of substance abuse, Mealy said. Her fiance, Robb Simmons, and Smiley's stepfather began searching for Smiley and her son, Azriel, after she didn't arrive at their planned meeting spot Saturday. Azriel is a second-grader at Vinland Elementary in Poulsbo, Wash. North of Tacoma, according to school principal Charley McCabe.

"I have no idea of why she would have ended up down that road," Simmons wrote on his Web site.

Mealy said Smiley has "no friends or relatives or lovers or boyfriends in Olympia or Thurston County."

"Somebody somewhere knows something," Mealy said. "She could be missing voluntarily. Something untoward could have happened to her. She could have done something untoward to her son. We have no clue."

Anyone with information on Smiley and her son's whereabouts should call Thurston County Crime Stoppers at 360-493-2222 or the Thurston County Sheriff's Office at 360-786-5500.