Franklin County Sheriff Jeff Richards said in a statement that remains recovered in eastern Kansas on Saturday are believed to those of Lana Leigh Bailey, a child that authorities previously said they presumed dead.
"I want the family of Lana, and all the victims, to know that this investigation will continue until we are confident we have collected as much evidence as we can to ensure justice is served on behalf of all four victims," Richards said in a statement.
Richards said the body was discovered by an Osage County sheriff's deputy who was searching an area for items that could be connected to the deaths reported May 6 at a farm home in nearby Franklin County.
Kyle Flack was charged Friday with capital murder in the deaths of Lana's 21-year-old mother, Kaylie Bailey, and 30-year-old Andrew Stout. The 27-year-old convicted felon also was charged with multiple counts of first-degree murder in those deaths as well as that of 31-year-old Steven White, authorities have said.
The evidence collected Saturday when the child's body was recovered led investigators to believe it was Lana, his statement said without elaboration.
"We hope that a forensic examination will make a final identification," Richards added. "Until the identity is confirmed investigators will continue following up on all tips, leads and information connected to this crime."
The statement did not provide any details of where the body was discovered or how the infant had died.
Richards told the Associated Press by telephone early Sunday that he would not have any further details beyond the statement. The Franklin County sheriff's office said its next scheduled statement on the investigation would be Sunday afternoon.
On Saturday, search crews had deployed using boats and sonar equipment in search of the child. Earlier authorities had said investigators were scouring ponds and other waterways in the area looking for the child's body.
The investigation had included searching the farm and other rural areas in the 50-mile stretch between Ottawa and Emporia, where Kaylie Bailey's car was found Tuesday.
Franklin County Attorney Stephen Hunting said Friday that a firearm was used against the victims at the farm, but didn't elaborate on whether that meant they were fatally shot. Authorities have not commented on a motive.
Richards said earlier that the extensive investigation of what he called a "horrific crime" had taken a toll and that members of the investigative team have required medical attention after searching in difficult areas. Others sought counsel from a chaplain.