OLYMPIA, Wash. -- The search continues for a mother and her 8-year-old son who mysteriously disappeared over the weekend. Their van was found partially submerged in Puget Sound.

Shantina Smiley, 29, had been driving her son, Azriel Carver, in the van from their home in Silverdale to visit relatives in Castle Rock, where she grew up.

TIMELINE: Last Known Locations Of Missing Mom, Boy
SLIDESHOW: Mother, Son Disappear; Van Found

Sheriff's investigators said somehow the Dodge Caravan ended up partially submerged in Dana Passage with its doors open. To get there, investigators said, the driver had to take a dead-end road, go down a winding driveway and onto the beach.

Smiley's fiance, Robert Simmons told KIRO 7 Eyewitness News that he's worried.

"It's nerve-wracking. It's very scary. It's not her character. She's never late. She's never missing and now she's missing," Simmons said in a telephone interview.

Simmons said Smiley left home Saturday afternoon and that she called him once from a pay phone to say she forgot her cell phone. Simmons has posted information about the events leading up to and following Smiley's disappearance on his Web site http://robbsimmons.com.

When asked whether Smiley may have become lost or was the victim of a crime, Chris Mealy of the Thurston County Sheriff's Office said, "We have no idea what happened."

Investigators said Smiley and her son left Silverdale at about 5 p.m. on Saturday and that surveillance video showed the two at a West Olympia mini-mart at 7:50 p.m. She told clerks there that she was lost and video showed her looking at a map of downtown Olympia.

Her next known stop was the Martin Way Diner on Fourth Avenue East in Olympia. She stopped there at about 9 p.m., ordered food, but left without taking it. Workers said she appeared to have trouble staying awake and she fell in the parking lot.

Smiley was then traced to a grocery store in Boston Harbor at 9:50 p.m. and then she stopped at the home of Dennis Williams in the 1400 block of 46th Avenue Northeast at about 10 p.m.

“She said, ‘I'm lost,’ and ‘Can you help me?'" Williams said. "She was obviously scared and we gave her directions. We let her use the phone. She called her grandfather I guess."

Smiley’s grandfather, Silas Smith, said she called and said that Williams had given her directions and she was hoping to head to the freeway.

"She said she was lost really lost, but she was doing fine," Smith said.

Smiley asked for directions to the freeway at Williams’ home, but turned the wrong way. A short time later, another camera at a north Olympia gas station shows her driving through the lot towards town.

Smiley was with her son -- and no one else -- according to witnesses and store surveillance video, investigators said.

She ended up on Zangle Road Northeast where she drove her van down a private road and onto the beach, where the vehicle got stuck, the sheriff's office said.

A homeowner near the beach called 911 Sunday morning when he saw the van partially submerged in the water.

In the a recording of the 911 call the homeowner says: "It looks like they went down last night some time, doors are all open."

Dispatcher: "Do you see anybody inside?"

Homeowner: "No, I'm pretty sure they walked out. I'm just surprised they didn't come up and ask for help."

A wallet containing the 29-year-old's driver's license, some cash and credit cards was found in the van, but neither she nor her son was anywhere in sight.

"No evidence of foul play was observed in the van," the sheriff's office said in a news release.

Investigators searched the bay by boat and did a door-to-door canvass on Sunday, but found no new leads.

"I hope they are together and I hope that they are safe," Simmons said.

“It doesn't make sense, that's why I'm so scared," said Simmons’ daughter.

Scent dogs and divers also aided in the search Monday, but they didn’t find any sign of Smiley or her son.

Friends and family described Smiley as a responsible, mature, rational woman. She has no history of substance abuse, and "no friends or relatives or lovers or boyfriends in Olympia or Thurston County," said Mealy.

Smiley's son, Azriel, is a second-grader at Vinland Elementary in the North Kitsap School District, according to school principal Charley McCabe.