The Polk County Sheriff's Office said the body of 10-year-old Reilly Scarbrough was found Saturday in a wooded area near Hatfield in far western Arkansas.
The discovery comes after the boy's sister, Acelynn Wester, was found Friday near Cove and near where the body of the children's 43-year-old mother, Bethany Jo Wester of Mena, was found Tuesday.
The woman's uncle, 66-year-old Steven Payne, was found dead Thursday in his home in Hatfield, about 4 miles north of Cove, about 120 miles southwest of Little Rock.
Sheriff Scott Sawyer told KARK that the boy's body was found with help from an inmate at the county jail, who had been arrested Wednesday on unrelated drug charges.
Suspected causes of the deaths of the four have not been released, but Sawyer said they are considered homicides and the inmate is a suspect in the deaths.
Sawyer said he "anticipates that capital murder charges will be filed" against the inmate, who is believed to have been Bethany Wester's boyfriend, but is unrelated to the children.
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