A massive manhunt for a missing Pennsylvania mother and daughter who allegedly were kidnapped after a minor car accident turned up no sign of the pair Wednesday, as the mystery into what happened to them deepened.

Police are planning to examine the silver SUV belonging to Bonnie Sweeten, 38, that was found in Center City, Philadelphia, before dawn.

Sweeten reportedly called 911 Tuesday and said she was locked in the trunk of a car after she and her 9-year-old daughter Julia Rakoczy were kidnapped in broad daylight.

"Based on what she says, they supposedly took her car and she was put in another car, but right now that's all we have to go on," said Philadelphia Police Lt. Frank Vanore, who heard the tapes. "It definitely sounds like she's afraid. ... But it's hard to tell what's going on."

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Detectives and reporters have been puzzled by holes in Sweeten's story, and FBI spokesman J.J. Klaver confirmed the existence of "inconsistencies" in her account of the accident and abduction. But he declined to elaborate and said those aren't the focus of the investigation.

"We're not concerned about any inconsistencies," he told FOX News. "Our main concern is finding that young girl and her mother."

In at least two cell phone calls she said she was making from a locked car trunk, Sweeten told emergency dispatchers that she and her daughter were snatched in the middle of the day Tuesday by two black men who rear-ended their SUV in suburban Philadelphia, according to police.

Though Sweeten, of Feasterville, Pa., implied her daughter was with her, the girl is not heard on the tapes, Vanore said.

Authorities haven't found either Sweeten or Julia after the early-morning discovery of their vehicle in Philadelphia Wednesday.

"We are treating this as an abduction," Klaver told FOX News. "We're aggressively pursuing leads."

The FBI joined the case along with local police in Upper Southampton Township, where Sweeten's vehicle was reportedly bumped from behind on a busy road. No witnesses have been located who saw the accident the missing mother described.

The 911 calls were made in downtown Philadelphia, about 20 miles from the site of the reported fender-bender and abduction, starting at about 1:45 p.m. Tuesday.

When investigators arrived at the scene, they found no evidence of the crash.

Klaver said authorities discovered the 2005 GMC Denali SUV about 1:30 a.m. Wednesday at 15th and Chestnut streets in Center City, two blocks from where a cell phone tower picked up one of Sweeten's 911 calls.

There was a parking ticket on the windshield with a time stamp indicating it was placed there about 20 minutes after Sweeten dialed 911 from a suburb that is at least a 40-minute drive away.

Sweeten's ex-husband and Julia's father Tony Rakoczy said the sequence of events doesn't add up.

"I don't think it makes any sense, the timeline and everything else," Rakoczy told FOX News on Wednesday.

Julia attended elementary school in Bensalem until she was withdrawn from classes May 1, said Susan Harder, an administrative assistant with the Bensalem Township School District.

Tony Rakoczy said there is no significance to the fact that she was pulled out of her school earlier this month, saying she was immediately placed in a different school.

"Hyping that up isn't helping," Rakoczy told FOX News. He didn't elaborate on why his missing daughter switched schools.

Sweeten has two other daughters, an 8-month-old with her current husband and a 15-year-old from a previous marriage.

Sweeten's oldest daughter Paige wrote on Facebook, "im asking everyone, to please pray for my mom and sister."

The missing mother, who is white, described her abductors as black males — but gave few details of their appearance, Vanore said.

"It was pretty generic," he said.

It is not clear whether Sweeten knew her alleged kidnappers.

Tony Rakoczy said on NBC's "Today" show that he doesn't understand why the abductors would hold onto his ex-wife and daughter.

"We don't have any money," he said.

He said he and Sweeten had stayed on good terms since the 2003 divorce and he didn't know why anyone would want to hurt her.

"I'm still in shock," he said. "She's a great mother."

Court records show that there are no continuing disputes between the couple since their divorce was finalized, according to the Inquirer.

Sweeten has since remarried Richard Sweeten, who runs a landscaping business, the paper said.

She sounded genuinely terrified in 911 calls saying she and Julia had been kidnapped by two men and stuffed into the trunk of a dark-colored 1990s Cadillac, authorities said.

"It seems like a very distressed call," Vanore told the Philadelphia Daily News. "You could tell she was scared."

On Tuesday night, a black Cadillac with damage to the front end was impounded, according to the Inquirer, but police said it didn't appear to be connected to the case.

Police were still searching for the Cadillac reported to have bumped Sweeten's vehicle.

The Denali was towed to police in Upper Southampton, where police planned to get a search warrant to inspect it. Detective Craig Rudisill declined to comment on any visible damage.

An Amber Alert was issued for Julia, who is described as 4 feet, 1 inch tall, weighing 59 pounds, with long, brown hair, blue eyes and a birthmark on her forehead.

Sweeten is 5 feet, 11 inches tall, weighs 130 pounds and has blond hair and blue eyes.
Julia's father told the Inquirer that his little girl plays softball and "loves the Phillies."

"She always dances around the house," he said.

A man at Sweeten's home refused to comment Wednesday and asked reporters to leave.

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The Associated Press contributed to this report.