Just days away from her due date, Amanda Jones (search) was thrilled about the upcoming birth of her baby boy.

When she left work Friday, where co-workers had recently thrown the single mother a baby shower, the last thing she said was she'd see them Monday.

But Jones, 26, hasn't been seen since Sunday afternoon, when she was at the Hillsboro Civic Center horse-show grounds in Jefferson County, south of St. Louis (search). Jefferson County Sheriff Glenn Boyer said her unlocked car was found, but there was no sign of Jones.

Jones went to the civic center to meet with Bryan Westfall (search), who relatives said is the father of her unborn child. His lawyer, Kevin Roberts, said Westfall has met with police four times since her disappearance. "He's tried to be as cooperative as possible," Roberts said.

Roberts would not discuss the conversation between Jones and Westfall on Sunday out of respect for their privacy. "It was cordial," he said, noting that Westfall is praying for her safe return.

Westfall doesn't know if he is the father of Jones' unborn child, Roberts said.

Jones' younger sister, Carrie Propst, 18, said family members have papered the region with flyers about her missing sister.

Authorities are doing what they can to search for Jones, Propst said. "We just wish it could be faster, so we could find her and bring her and the baby home soon."

Propst said Jones was due to give birth next week, and couldn't easily walk in her ninth month of pregnancy, making family members all the more inclined to think she wouldn't have voluntarily left the area.

Boyer said a 20-member task force is working to find Jones. Authorities searched a wooded area Monday, have flown over the region looking for her, and have put out word nationwide about Jones' disappearance.

Boyer said that despite some suspicious circumstances, there has been no physical evidence and no witness indicating a crime. He said there are no suspects.

Jones, 5-8 and 225 pounds, has blue eyes, blond hair and a dolphin tattoo on her left upper torso. She was last seen wearing a pink shirt and pink sandals.

Anyone with information is asked to call 636-797-5515.