The mother of a 6-year-old girl was taken into custody Sunday after the child and her grandfather were found murdered in Lakeland, the Polk County Sheriff's office said.

Mark Weekly, 50, and Meredith Jessie were last seen on July 18 at Weekly's home on Drane Field Road, where Meredith was left in Weekly's care. They were reported missing Saturday by the girl's mother, Cheyanne Jessie.

Jessie is charged with two counts of first-degree murder and one count of tampering with evidence.

"Is it bizarre? Yes," said Sheriff Grady Judd. "It is one of the most horrific cases we can imagine. Nothing’s more horrific than the murder of a child except when it’s done by a parent."

Detectives believe Jessie killed her father and daughter on July 18. Then investigators say the 25 year old left their bodies inside of her father’s home for days before putting the remains in duffel bags and hiding them behind a neighbor’s shed.

Judd said he believes Jessie reported the two missing Saturday because she kept getting questions about their whereabouts.

“She felt the noose tightening because her stories weren’t making sense," Judd said. "'Oh, he's in Georgia and I’ve talked to him and my daughter’s in Georgia.' And I suspect when we get through different witnesses that we’ll find some family or friends have been beginning to question, you mean, 'your daughter’s been gone two weeks now?'"

Judd said they believe a gun and a knife was used. And when they asked Jessie why she did it, she said she was defending herself from her dad and she admitted to having problems with her daughter.

"She didn’t like her daughter," Judd said. "She was frustrated with her daughter. She was frustrated with the child and as a result she didn’t want the child to mess up the relationship she had with the boyfriend."

Jessie has been booked into the Polk County Jail. She will make her first appearance Monday.