Authorities who have questioned Sven Jaschan got the impression his motive was to gain fame as a programmer, prosecutor Detlev Dyballa said.
He labeled as speculation news reports that he may have created the disruptive program to drum up business for his mothers computer store, PC-Help, in the small town of Waffensen.
"One can never rule out anything, but there are no facts to suggest it," he told The Associated Press by telephone.
Jaschan was arrested Friday at his mothers house, where police said agents found him sitting at his computer. Investigators say the machine contained the worms source code.
Earlier Friday, investigators said, Jaschan unleashed the new "Sasser e"—a failed attempt to limit the damage caused by the four previous versions.
Frank Federau, a spokesman for the state criminal office in Hanover, said the worm was "a slightly modified form" of the program that raced around the world over the past week, exploiting a flaw in Microsofts Windows operating system.
"He did it with good intentions, but it had exactly the same damaging effects," said Sascha Hanke, a Microsoft data protection official in Germany.
Like the other versions, the new variant—which notified users of a Microsoft patch against Sasser—caused computers to crash and reboot.
"The cause was erroneous programming of the virus," Hanke said. Police have said Jaschan was responsible for all versions of Sasser as well as the "Netsky" virus.
He is being investigated on suspicion of computer sabotage, which carries a maximum sentence of five years in prison. He was released pending charges after questioning last Friday, where he admitted creating Sasser, police said.
A trial could begin at the end of June, Dyballa said.