The five-year-old boy being held hostage for a fourth day has been crying for his mother as police continue to plead with the 'survivalist killer' who kidnapped him after it emerged today he may have enough supplies to last for months.

Jimmy Lee Dykes is accused of shooting a school bus driver dead and grabbing the kindergartner before escaping to an underground Doomsday bunker which he has been building by hand for months, neighbors said.

Police have settled in to Midland City, Alabama, for the long haul as they continue to negotiate with the 'survivalist' and plead with him to let five-year-old Ethan go without harm.

Though he is not believed to have hurt Ethan, Dykes has a violent reputation in the quiet town after he allegedly beat his neighbor's dog to death with a lead pipe and would threaten to shoot any child that would come on to his property.