The Wayne County Sheriff's Department arrested a neighbor, 24-year-old Jarrod Metsger, Sunday afternoon.
Police said Metsger is a neighbor and acquaintance of the Murphy family, newsnet5.com reported. A motive has not yet been established for the killing, a sheriff's statement said.
Saturday evening, deputies responded to the mobile home park in Smithville after getting a report that the girl, Reann Murphy, was missing. The child was last seen playing outdoors in a shared area within the mobile home park.
Deputies, firefighters, civilians and other law enforcement officers searched the area for hours before finding the body.
"Any violent death is troubling but the death of a child is much more so. We will leave no stone unturned as this investigation continues" Sheriff Travis Hutchinson said.