"We have reasonable suspicion that this is the body of Navaeh," Monroe County Sheriff Tilman Crutchfield said during a press conference this morning, adding that the body "in appearance appears to be the same age, size and sex of Nevaeh Buchanan."
An autopsy will be done today to confirm the identity and determine a cause of death, but Crutchfield said there were no visible signs of abuse. The body, he said, had been buried along the River Raisin "for awhile."
He declined to comment specifically about how the body was buried only that it had some type of concrete or cement on the top. He also would not say what else investigators recovered from the grave.
Nevertheless, the little girl's grandmother, Sherry Buchanan, told ABC affiliate WXYZ Thursday night that she refuses to believe it until she's got proof.
"Until they have DNA testing through [Neveah's mother] and match the blood type and eveything and make sure ... I'm just holding onto that thought in my heart," she said.
Buchanan told WXYZ-TV that he had asked police for a picture of the body, but her request was denied.
Backing away from previous statements naming two sex offenders as persons of interest, Crutchfield would not comment on any suspects. George Kennedy, 39, and Roy Lee Smith, 48, both said to be acquaintances of Nevaeh's mother Jennifer Buchanan, are being held on probation violations simply for being associated with a child.
Crutchfield said Jennifer Buchanan was cooperating with police, but would not comment when asked if they believe she knows something about the crime or who murdered her daughter.
The murderer, he said, could still be free in the community.
"In my opinion it is a very sick or disturbed person we are looking for, a person who is able to abduct and murder an innocent 5-year-old child," he said.
A Gruesome Find for Family of Fishermen
Investigators, Crutchfield said, are expected to be back today at the scene, which has been limited to law enforcement and residents.
Guy Bickley, along with his son and father, found the little girl's body while they were fishing along the riverbank.
Ryan Bickley, 15, told The Associated Press his father had spotted a block of poured cement and was hit by the smell he likened to a decomposing body.
Ryan told the Associated Press that the smell "overwhelmed them" as his father moved closer to chip away at a piece of the cement, which revealed what appeared to be human skin.
Nevaeh's family members told the Detroit affiliate that they are even more suspicious now of George Kennedy, a 39-year-old registered sex offenderand friend of Nevaeh's mother, who has been named a person of interest by Monroe County police.
Kennedy, who is jailed on probation violations for simply being associated with a child, works with cement in the area where the body was found, according to the family's statements to WXYZ.
Whoever the killer is, Sherry Buchanan told the station, "I hope they give him everything that's got coming to him."
"I told the officer, I said, 'You're not going to be able to protect him,'" she said. "I said 'One way or another, I said, I am going to get to him."
Who Kidnapped Nevaeh?
In addition to Kennedy, police have also named a second person of interest in the case, another sex offender who knew Jennifer Buchanan. That man, Roy Lee Smith, 48, was released from prison last year after serving 15 years for multiple criminal sexual misconduct convictions, according to the Michigan Department of Corrections Web site. Other convictions include mulitple counts of larceny.
He, too, was jailed for probation violations.
When asked last month if Buchanan herself was a person of interest, Crutchfield replied "no comment," according to ABC affiliate WXYZ.
Smith's mother, Donna Smith, told ABCNews.com last month that her son is not involved in Neveah's disappearance.
"I don't believe my son has anything to do with this," Donna Smith said, adding that his previous conviction was because a 24-year-old girl he was with "decided to holler rape."
A bloody towel and a blood-stained tool, along with photos of young girls, were among the evidence confiscated from Kennedy's motel room and in a van that also has ties to Smith.
Donna Smith said her son had traded the van to Kennedy about a week and a half ago and got Kennedy's Thunderbird in return.
Crutchfield said police had received about 530 tips in the case.
Monroe County police spokesman Maj. Dan Motylinski told ABCNews.com last month that they will follow up on every tip that comes in.
"All we can do is hope it's a recovery of her alive and well," he said.
He declined to comment on reports from the Detroit Free Press that Buchanan told reporters that investigators had seized a letter she had written to Kennedy, but tore it up before it was sent.
She told the newspaper the letter was completely innocent and that it made no mention of Neveah or Kennedy spending time with her.
In 1998, Kennedy, 39, was charged with a felony for having sex with a girl under 16. That charge was later dismissed, court records show.
In addition to the 1998 charge, court records show that by 2002, Kennedy had been charged with a home invasion and accosting a 13-year-old girl. Kennedy's former court-appointed lawyer Peter Sickels told ABCNews.com that the charges were combined in a plea deal that allowed him to be released from prison in 2003.
The Associated Press contributed to this report.