Ryan Schallenberger may have just been bragging, state prosecutor Jay Hodge said
"He may have tried to make something and didn't finish it," Hodge said. "The kid is either just making it up or disposed of them."
A search that included the use of a bomb-sniffing dog found nothing Saturday, when the boy was arrested after his parents discovered he had ordered ammonium nitrate on eBay.
Authorities have said Schallenberger could have assembled bombs within minutes with materials they found at the home. A journal found there contained bombing plans, including a hand-drawn map of Chesterfield High School, and hate-filled pages that lauded the Columbine killers in Colorado, police said. They also said they found an audiotape that Schallenberger wanted played after he died.
Hodge on Tuesday said the 50-page journal also contained some attempts at self-analysis and that the teen knew that what he was planning was wrong. "He had a temper," the prosecutor said.
The journal did not name a specific target for an attack nor did it specify whom Schallenberger wanted to harm.
Ashley Waters, one of Schallenberger's classmates, told the CBS Early Show, "What he did is completely out of his character. He's really nice, he talks to everybody, everybody talks to him. Nobody picks on him, so we don't really know what's going on."
Schallenberger, 18, faces several state and federal charges, including attempting to use a weapon of mass destruction, which carries a possible life sentence.
Authorities initially said the teen had ordered 10 pounds of ammonium nitrate, but Hodge said Wednesday the material actually weighed 20 pounds.
Ammonium nitrate is a common fertilizer that has been a main ingredient in bombs used in attacks across the world, including the deadly 1995 Oklahoma City bombing that destroyed a federal building.
Schallenberger, a top student at the school, purchased the ammonium nitrate from a seller in Kentucky, federal officials said. A spokeswoman for eBay has said the California-based company has been cooperating with authorities in their investigation.
CBS News correspondent Mark Strassmann reports that by the time Schallenberger's parents began to seek help for their son, the bomb-making supplies that he had ordered using the Internet were already in the mail.
After authorities were alerted by his parents, deputies searched Schallenberger's home and seized several items, including a laptop computer, which was being analyzed by the State Law Enforcement Division, Hodge said. They also found an audiotape he left to be played after his death.
Schallenberger's mother and stepfather, John and Laurie Sittley, have not commented publicly. Their phone number is unlisted and their home off a dirt road about 10 miles from the school has "No Trespassing" signs posted.
Federal public defender Michael Meetze, who represents Schallenberger, declined to comment Wednesday.
Schallenberger's attorney on the state charge, William Spencer, did not immediately return a call seeking comment Wednesday.
Chesterfield is a town of about 1,500 in the northeastern part of the state.