According to German news magazine Focus, the public prosecutor's office investigating the origins of the Sasser computer worm is looking at the involvement of the whistleblower. The person who tipped off Microsoft Corporation about the programmer responsible for writing "Sasser" is also being investigated for computer sabotage, according to the magazine. The public prosecutor's office has said five more people are under investigation in connection with the case, but has refused to confirm whether the whistleblower was among them. The main suspect is the 18-year-old Sven J. from northern Germany. Microsoft says that if the informer who gave them information was involved in spreading the virus the company will not hand over the €210,000 reward money.