The 17-year-old girlfriend of a missing Florida girl's father has taken a lie detector test, a local sheriff said.

He wouldn't reveal the results of the test, but the father, Ronald Cummings, and his girlfriend, Misty Croslin, said Thursday night during an interview with FOX News' Greta Van Susteren that they both submitted to polygraphs and both "passed."

Croslin was the one who reportedly discovered that 5-year-old Haleigh Ann-Marie Cummings had vanished from her bed before dawn on Tuesday.

Several people have been interviewed by police and the FBI, and all have been offered the chance to take a lie detector test, Putnam County Sheriff's spokesman Gary Bowling said.

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Detectives believe Haleigh was abducted — and they aren't overlooking anyone, including family members, as suspects.

Haleigh is 3 feet tall with blond hair and brown eyes. She was last seen wearing a pink shirt and underwear.

Hardy said ground searches continued for a third day on Thursday. Bloodhounds have been used, but haven't turned up any clear evidence.

"We have nothing definitive to say where the child is based on the bloodhounds," Hardy told reporters at a Thursday news conference.

He said evidence has been collected from the mobile home where Haleigh lived with her 3-year-old brother Junior, her father, Cummings, and Croslin — but declined to describe it.

"I can't discuss what evidence was taken into custody," Hardy said. "I don't want to reveal what was found or not found."

Ronald Cummings, told FOX News' Greta Van Susteren that Croslin was watching his daughter while he was at work as a crane operator.

According to Cummings, Haleigh had gotten up to use the bathroom. When she didn't return, Croslin went to look for her and noticed the back door was open.

"I locked doors before I left for work. My child cannot unlock the deadbolt, you have to force the door shut all the way ... and she doesn’t open the door to strangers," Cummings said.

Croslin and Cummings called 911 after discovering the girl was missing, according to the police report. The tapes were released Wednesday.

In addition to Croslin, Cummings and the child's mother, Crystal Sheffield, as well as several others have been questioned in the case.

"It is never safe to say that a family member is not a suspect," Bowling said Wednesday. "However, all the world is a suspect right now."

Police have ruled out the possibility that the girl ran away.

"This child didn't voluntarily walk out of her home. If she did, someone took her," Bowling said.

Cummings, who has custody of Haleigh and her brother, said his daughter wouldn't leave on her own.

"I know somebody took her. I know for a fact she didn't wander off — she's afraid of the dark," Cummings told NBC's "Today" on Thursday.

Police said house-to-house searches of the neighborhood Wednesday found no evidence that the child wandered away.

Police had never been called to the home in the past — but there have been prior problems with Cummings, Croslin and the children, according to Putnam County Capt. Steve Rose.

"There have been some investigations done through the department of children and family," Rose told FOX News on Wednesday. He didn't elaborate.

John Harrell, spokesman for the northeast region of the Florida Department of Children and Families, said Thursday that his agency "was involved with the family." Harrell would not offer any details, citing state confidentiality laws.

Sheffield's mother, Marie, told Van Susteren that the children seemed to be doing well living with their father.

"Haleigh told us they’ve been hit, and stuff like that, but to this point, everything was fine," Marie Sheffield said.

There were still no firm leads in the case. Detectives wouldn't say whether Croslin, Cummings or anyone else in the family were a focus of the investigation.

Haleigh's grandfather, Johnny Sheffield, said he was distraught about the girl's disappearance and characterized Croslin as suspicious, though he admitted he didn't know much about her, according to MyFOXOrlando.com.

Sheffield told Van Susteren that her children loved their father's girlfriend, whom he'd been dating for 4 to 6 months.

"She seemed like a really nice person, but I never sat down and had a conversation with her," she said.

Appearing on FOX News on Thursday, Sheffield answered "yes" when asked whether it was true that Croslin had given conflicting statements to police.

The child's mother doesn't live in the area but traveled to Putnam County after she learned of her daughter's disappearance and has been interviewed, according to Rose.

"She is cooperating," Rose told FOX News on Wednesday.

Cummings said his girlfriend was awake and frantic after she found Haleigh was gone. But in the police report, obtained by FOX News, Cummings reportedly told officers that his "dumb bitch girlfriend" told him Haleigh was gone when he got home from work.

"Ronald said that he did not know what Haleigh was wearing, and that all he knew was that the back door was standing open. Ronald repeatedly said that someone had taken his child and also said 'When I find him I'll kill him,'" police wrote in the report.

He referred to a 9mm Beretta handgun he owns and said if authorities found his daughter's kidnapper, "he would shoot them through the back window of the patrol car," the police report said.

Deputies said Thursday they're in the process of questioning 44 registered sex offenders who live within five miles of Haleigh's home.

An uncle, Andrew Sheffield, believes she is alive, but the mystery of her whereabouts continues.

"It's fishy," he said. "Somebody knows something."

George Anthony, the grandfather of slain Florida toddler Caylee Anthony, met with Haleigh's father Thursday. Anthony said he was there simply to offer moral support.

Anyone with information about the girl is urged to contact the Putnam County Sheriff's Office at (386) 329-0800 or 911.

Click here for more on this story from MyFOXOrlando.com.

FOXNews.com's Catherine Donaldson-Evans and The Associated Press contributed to this report.