A neighbour of a man who has taken a child hostage in an underground bunker said he had been building it for months.
Police said Jimmy Lee Dykes killed school bus driver Charles Albert Poland, 66, on Tuesday, before abducting a five-year-old boy and taking him to his home-made bunker at his rural Alabama property.
Since the standoff, negotiators have been trying to persuade the 65-year-old loner to surrender through a ventilation pipe connected to the bunker.
The Vietnam veteran has been described by neighbours as a menacing figure who holds anti-government views.
Neighbour Michael Creel said the suspect spent two or three months constructing the bunker, digging into the ground and then building a structure of timber and plywood, which he covered with sand and dirt.
He said Dykes put the plastic pipe underground from the bunker to the end of his driveway so he could hear if anyone drove up to his gate.
When Dykes finished the shelter a year or so ago, he invited Mr Creel to see it - and he did.
"He was bragging about it. He said, 'Come check it out'," Mr Creel said.
He added he believes Dykes' goal with the stand-off is to publicise his political beliefs.
"I believe he wants to rant and rave about politics and government. He's very concerned about his property. He doesn't want his stuff messed with," said Mr Creel.
Neighbours said Dykes once beat a dog to death with a lead pipe and threatened to shoot children for setting foot on his property.
Dykes had been scheduled to appear in court on Wednesday to answer charges that he shot a gun at his neighbours in an argument last month about a speed bump.
James Arrington, police chief of the neighbouring town of Pinckard, said the storm shelter was about 4ft underground with about 6ft-by-8ft of floor space.
"It's pretty small, but he's been known to stay in there eight days," he said. "He will have to give up sooner or later because (authorities) are not leaving."
Officials have confirmed the boy has Asperger's and attention deficit hyperactivity disorder, or ADHD. Police do not believe he has been harmed.
Republican lawmaker Steve Clouse, who represents the Midland City area, said he visited the boy's mother on Thursday and that she is "hanging on by a thread".