Putnam County Sheriff Jeff Hardy said at a news conference Thursday afternoon that investigators believe Haleigh Cummings is most likely dead and persons of interest have been identified.

Investigators continued their search of the St. Johns River for a third day on Thursday in connection with the disappearance of the 6-year-old Satsuma girl, and Hardy said items have been recovered. He said it's unknown if the items are related to the case, and they will be sent to labs for analysis. Sources confirmed to Channel 4 that two cinder blocks were pulled from the river.

The sheriff said the search at the Shell Harbor Boat Ramp was the result of information obtained during interviews. In an e-mail Friday from the attorney for Hank Croslin Jr., Misty Cummings' brother, the attorney said Croslin took a polygraph test last week and met with investigators Monday to discuss the events of the night of Haleigh's disappearance. The attorney said Croslin took investigators to the Shell Harbor Boat Ramp, where the search began the next morning.

Hardy said he's confident in calling this a homicide investigation based on information obtained by investigators over the past few weeks, and he said some "people are starting to cooperate" and talk, though he did not say who he was referring to.

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Hardy said no one has been arrested, but investigators are "working on building a case."

The sheriff said of Misty Cummings, the last person to see Haleigh the night she vanished, that she has been acting more calm and, "I think she's coming to realize she's in trouble."

On Wednesday afternoon, Misty Cummings was seen on a dock at the river talking with investigators. She was later returned to the St. Johns County Jail, where she's being held on drug trafficking charges.

Investigators said when they got the tip that led to the river, they were encouraged it would lead to something significant because it's a place they've never searched before, it's in a remote area and it's a logical place to get rid of something. Hardy called the location Thursday a possible crime scene.

Putnam County investigators flew to Antioch, Tenn., Tuesday night to question Joe Overstreet, a cousin of Misty Cummings. When Haleigh vanished from her father's Florida mobile home 14 months ago, Overstreet said he was in Satsuma on vacation. Investigators have since flown back to Florida. They said they've interviewed Overstreet several times before.

Overstreet and Cummings' grandmother, Flora Hollars, who also lives in Antioch, said it was her tip that led investigators to search the St. Johns River. Though Hardy said the tip did not come from Tennessee, but from a source.

"What I've heard is they're looking for particular items now, but they've not told me what kind of items," Hollars said.

Hardy said he met with members of Haleigh Cummings' family Tuesday afternoon, but he would not say what he told them. Haleigh's great-grandmother Annette Sykes told Channel 4 after the sheriff's announcement Thursday that that's what he told the family. Still, she said she will hold out hope that Haleigh is alive.

"My mind tells me that that may be true, but my heart says it's not," Sykes said. "And until they can bring me something to prove to me that she's not alive, I'll continue to believe that she is. People can make fun of me and talk about me and our whole family, basically. But if they can't prove to me somehow that she's dead, I'll just keep on believing she's alive."

Teams stopped searching as the sun went down Tuesday and Wednesday nights, but they were back in the water early in the morning each day after. They planned to do the same Thursday night and begin searching again Friday morning.

Florida Fish and Wildlife Conservation Commission team member Ben Allen said the water was clouded with almost no visibility for most of the day. Divers from at least four agencies or counties helped in the search, using floodlights to help see underwater.

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The blond, curly-haired girl disappeared from her father's doublewide mobile home in Satsuma, a rural community in southern Putnam County in February 2009.

Her father's 16-year-old live-in girlfriend, Misty Cummings, was baby-sitting at the time. She told investigators she awoke at 3 a.m. Feb. 10 to find the girl gone and a back door propped open with a brick.

Within a month, Haleigh's father, Ronald Cummings, married Misty. They have since divorced.