They also thanked the suspect for taking care of the child as the standoff marked its fifth day.
In a brief news conference Saturday morning, Dale County Sheriff Wally Olson said Jimmy Lee Dykes has told officials that he has blankets and an electric heater in the bunker. Olson said Dykes has allowed authorities to deliver coloring books, medication and toys for the boy.
"I want to thank him for taking care of our boy," Olson said. "That's very important."
Investigators say Dykes shot and killed a school bus driver Tuesday and took the boy to the bunker on his property in rural Midland City.
The sheriff would not say whether Dykes has made any demands, adding that he is limited in the details he can release.
Negotiators were still trying Saturday to persuade Dykes to surrender. Authorities say he and the boy are holed up in a small underground room on Dykes' property that authorities likened to a tornado shelter, something common to this area of the South. The bunker has electricity, food and a TV.
The 5-year-old's mother has told officials that her child has Asperger's syndrome, an autism-like disorder, as well as attention deficit hyperactivity disorder, or ADHD.
Dykes was known around the neighborhood as a menacing figure who neighbors said once beat a dog to death with a lead pipe, threatened to shoot children for setting foot on his property and patrolled his yard at night with a flashlight and a firearm. He was due in court Wednesday to face charges he shot at neighbors in a dispute last month.
The Associated Press contributed to this report.