Kentucky State Police said remains found Friday during a search of the family residence of missing 8-month-old Miya Rudd likely belong to the girl.
"Kentucky State Police detectives located an infant's body consistent with Miya Rudd at 1:15 today," the agency said in a statement.
The hidden body was decomposing, it said.
The remains were found in a corner of the home, which was full of debris, Trooper Corey King told NBC affiliate WFIE of nearby Evansville, Indiana.
"Not the results we wanted," he said, "but really expected."
Preliminary findings from a medical examiner, including possible identification, could come as soon as Saturday, King told the station.
Law enforcement officials said that with the discovery, the search now transitions to a criminal investigation.
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The girls' parents, Tesla Tucker, 29, and Cage Rudd, 30; paternal grandparents Billie J. Smith, 49, and Ricky J. Smith, 56; and a fifth person, identified as Timothy L. Roach, were arrested in early June on drug charges.
All except Roach are from Reynolds Station, about 90 miles southwest of Louisville, police said. Roach is from Owensboro, about 25 miles west of Reynolds Station, they said.
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It's not clear if they have retained legal counsel. The public defender for the region did not respond to a request for comment.
Investigators looking for Miya spotted drugs, including pills containing fentanyl, "in plain sight" at a Motel 6 where her parents were contacted, King said previously. The pair also faced allegations of child abandonment.
Grandmother Billie J. Smith was contacted as part of the investigation and had an active warrant related to a domestic incident, according to state police and WFIE. Roach was at her residence, in a driveway, and allegedly tossed drugs as police arrived, they said.
On Wednesday, Miya's maternal grandparents, Taletha and David Tucker, who have been raising her three siblings, were arrested based on warrants, WFIE reported, citing Kentucky State Police. The nature of the warrants was unclear.
They were initially booked into Daviess County Detention Center in Owensboro, the station said
It's not clear if they have retained counsel. The same public defender's office that would have jurisdiction should a judge decide to assign it did not immediately respond to a request for comment.
On Thursday, state police said a man who had been living with Miya's parents for six months, Brodie C. Payne, 28, was charged and accused of trafficking drugs, including methamphetamine, from the residence.
He was in custody based on other drug charges from May, the agency said in a statement.
It was not apparent if he has a lawyer.
On Tuesday, state police used cadaver dogs to search the woods near Miya's home for the missing girl. Police identified her in recent days as Maya Tucker, but they now appear to be using Rudd as her last name.
King told WFIE during an on-camera interview on Tuesday that state child welfare authorities had removed three of Miya's siblings from her home because of drug allegations and were planning to do the same with Miya before she went missing.
He said her umbilical cord tested positive for methamphetamine shortly after birth.
A family member told police she was last seen at the end of April, King said. When asked about her whereabouts, Miya's parents told investigators she had already been removed by the state Cabinet for Health and Family Services, he said Tuesday.
After checking, he said, investigators determined that wasn't true.
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