ORLANDO, Fla. -- Sources told Local 6 News on Tuesday that detectives investigating the disappearance of a missing 3-year-old Orlando girl are focusing on three key dates in mid-June and are trying to track the girl's mother's whereabouts during that time.

Investigators with the Orange County Sheriff's Office are trying to track Casey Anthony's whereabouts on June 16, 17 and 18 in connection to the disappearance of her daughter, Caylee Anthony. Casey Anthony reported her daughter missing in mid-July, 31 days after she said she last saw the girl.

Sources told Local 6 News that if something happened to Caylee, it may have occurred on June 16, a day after Father's Day.

June 17 is the day detectives said Casey Anthony borrowed a shovel from a neighbor of her grandparents. The same neighbor said she saw Casey Anthony strangely back her car up into the family's garage on June 18.

Sources said that detectives are trying to track Casey Anthony's whereabouts on the three key dates by using cell phone records. Local 6 News reported that investigators will perform a more thorough search for Caylee using cadaver dogs and search teams when they know more about Casey Anthony's whereabouts during the three days.

Casey Anthony was seen by her father, George Anthony, on June 16 wearing a white shirt and gray dress slacks. The slacks were later discovered in Casey Anthony's car after it was found abandoned at an Orange County Amscot and returned to the grandparents' home.

Casey Anthony's mother, Cindy Anthony, said she washed the gray pants but told investigators early on in the investigation about that fact. Detectives said they learned about the pants being washed about a week ago.

Casey Anthony remains held on $500,000 bond on charges of child neglect and filing a false statement.

2nd Search In 2 Days Called Off

For the second time in two days, Orange County sheriff's deputies and K-9 units performed a search for Caylee Anthony.

Orange County sheriff's deputies on Tuesday requested the assistance of Osceola County's K-9 unit and searched a wooded area near the home of Caylee's grandparents.

The search was called off and nothing was believed to have been found, Local 6 News reported.

On Monday, deputies searched a wooded area near Lee Vista Boulevard and Narcoossee Road.

George and Cindy Anthony are scheduled to visit their daughter on Thursday.

Local 6 News also reported Tuesday that DNA evidence from Casey Anthony's car, which was found abandoned last month at an Orange County Amscot, has not yet been returned from the lab.

Family Threatened Daily

Meanwhile, the family of Caylee Anthony continues to be threatened every day as a search for the child continues.

"We get threats every day," Cindy Anthony, said. "We get threats on our home phone and we get threats on our cell phone."

Casey Anthony's brother, Lee Anthony, canceled a scheduled Orange County Jail visit with his sister on Tuesday morning.

Casey Anthony's attorney, Jose Baez, said his client wants to talk with her family but is sacrificing for her daughter.

"It's not something she wants," Anthony's attorney Jose Baez said. "She wants to see her family. She wants to talk to her family but she's willing to sacrifice that for Caylee."

George Anthony was the last family member to see Casey Anthony, a visit that took place last Sunday.

Wednesday will mark one month since Casey Anthony was jailed in connection with the case.

Caylee Called?

Cindy Anthony said on Monday that she believes the missing girl may have made a call after she vanished -- which would be new information in the case.

"I believe my mother also heard Caylee during that time," Cindy Anthony said.

When Cindy Anthony was asked how Caylee would know her great-grandmother's phone number, she said the number was programmed into Casey Anthony's phone.

A sheriff's department representative is checking to see if Cindy Anthony has ever mentioned the call before.

Expert Discusses Liars

Family and friends have described Casey Anthony as a pathological liar -- a person who they claim has told one lie after the next, Local 6 reported.

Dr. Richard Hall, who is a forensic psychiatrist with patients who are both in and out of jail, said habitual liars often lie to feel good about themselves.

"It shows that I'm smarter than you are and it shows that I have some power over you," Hall said. "And it shows that I've got some power over you and that I can manipulate you."

Hall said people who lie often never come forward to tell the truth.

"People who are habitual liars continue to lie in captivity just like they lie in the general public," Hall said. "So, they tend not to change and suddenly want to tell the truth and get everything."

Hall said he can't comment specifically about the Caylee Anthony case but said it could take some time as investigators search for the truth.

Bond Motion Denied

On Monday, an appeals court has denied a motion to lower the bond for Casey Anthony.

The 5th District Court of Appeal in Daytona Beach denied Casey Anthony's motion for a rehearing. The motion was sealed.

"I still think that to this day, the bond is excessive and tantamount to no bond at all," Baez said.

Casey Anthony is being held on $500,000 bond on charges of child neglect, making false statements and obstructing an investigation. Police said she lied to them and didn't report her daughter, Caylee, missing for more than a month.

Grandparents Visit Detectives

The grandparents of Caylee Anthony met with detectives on Monday for about two hours.

George and Cindy Anthony were at the Orange County Sheriff's Office from about 9:30 a.m. until 11:30 a.m. in what they called an exchange of ideas.

Cindy Anthony said she talked with detectives about a phone call that Casey Anthony said she received in which she heard Caylee in the background. According to a search warrant, detectives said phone records show that the phone call never occurred.

"We discussed that with the deputies today. They're re-looking at the phone records because that's a misstatement," Cindy Anthony said.

A national search for Caylee continues.

Watch Local 6 News for more on this developing story.