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Detectives visited the grandparents of a missing Florida toddler to gather evidence Thursday and lake searches are planned for Friday, still calling the search for the child a "missing person case."

Orange County Sheriff's Office investigators arrived at the home of Cindy and George Anthony for a brief morning visit after being contacted by Cindy Anthony to discuss the disappearance of 2-year-old Caylee Marie Anthony.

Detective John Allen told reporters that it remains a "missing person case," adding "of course as evidence comes in that suggests otherwise, we’ll deal with that as well."

Diving crews from the department planned to launch a search Friday of one of lakes near the Anthony residence, according to MyFOXOrlando.com. Police said the searches are routine training exercises and happen monthly.

"Nothing is leading to her being in the water," Deputy Sheriff Carlos Padilla said. "It's just a training exercise."

Caylee's mother, Casey Marie Anthony, remains in jail on a $500,000 bond for allegedly failing to immediately report her daughter's disappearance and lying to police.

Speaking from her doorway, Cindy Anthony told a cadre of reporters that she had called police and that the family and investigators were working together as a team.

"We came together and got some stuff that we needed to have looked at and we’re all satisfied with that," she said.

Detectives left the Anthony residence with a new bag of evidence that may help with the search for the missing toddler.

The home visit Thursday comes a day after crime scene investigators searched the Orlando residence that the Anthony's daughter and granddaughter called home until the time of the little girl's disappearance on or around June 15.

They took away at least four bags of evidence. MyFOXOrlando.com reported that the latest, four-hour search yielded at least eight bags.

Thursday's visit is at least the fifth time they have been at the home. The Orange County Sheriff's Office called Wednesday's visit "routine" and said the girl — who turns 3 on Saturday — has not been found.

Meanwhile, a lawyer for Jesus Ortiz, a man who may be the late father of the missing child, told FOX News that Casey Anthony and Ortiz went to high school together, and that the young man's family is shocked by the news that their son may be the father. Ortiz died in a car accident about a year ago.

"The family has never heard of her," the lawyer, Bryan Crews said, adding, "Had he been the father of the child, they certainly would have known."

Detectives have told FOX News that they are looking into the possibility that Casey Anthony, 22, impersonated the baby sitter who she says took Caylee. She may have signed the sitter's name during a visit to an apartment complex and written in a visit date within the time frame of the child's disappearance.

Casey Anthony told detectives that a woman named Zenaida Fernandez Gonzalez had been Caylee's babysitter for the past two years and told them where her apartment was. But when police went to the apartment she said belonged to the alleged baby sitter, they learned it had been vacant for almost five months.

Since then police have spoke to a woman by that name, but that Zenaida Fernandez Gonzalez did not recognize Caylee or her mother. Police said that particular name is common and believe it could be a coincidence.

Detectives interviewed the woman twice, and she dispelled any concerns with her involvement in the case, Padilla said.

Cindy Anthony told reporters there are nine other people in the area with the same name, and that this specific woman is not the correct one.

The family has said Casey Anthony fears that Caylee's life is in danger.

Cindy and George Anthony have acknowledged that their daughter stole gas cans from their shed and has lied to them. But they continued to maintain her innocence in Caylee's disappearance.

The Anthonys told FOX News' Greta Van Susteren that they believe Casey when she says she knows who has Caylee but isn't sure where her little girl is.

The grandmother said Casey has told her what happened to Caylee "in her way," but she couldn't disclose many details.

"I can't reveal that," Cindy Anthony said in an "On the Record" interview that aired Tuesday.

Click here to watch portions of the interview.

The Florida State Attorney's Office filed formal criminal charges against Casey Anthony on Tuesday.

She was charged with one felony and one misdemeanor offense in addition to the child neglect charge she already is facing. She is scheduled to be arraigned Aug. 21 but does not have to appear in court because her attorney submitted a written not guilty plea.

It took Casey Anthony more than a month to report the child missing, which she did on July 15.

Detectives reported smelling a strong odor of decomposition in the trunk of a car Casey Anthony was using. They said they also found hair samples similar to those belonging to Caylee.

Click here for more from MyFOXOrlando.com.

FOX News' Phil Keating, Ian Rafferty, Catherine Donaldson-Evans and The Associated Press contributed to this report.