Computer glitch deletes German crime cases In the latest incident a technical problem prompted computers at the federal police headquarters (BKA) to erase evidence such as bugged telephone conversations, text messages, emails and faxes over two months covering the end of 2011 and the beginning of this year. "When original law enforcement data from surveillance operations is lost and there is no verbatim transcripts of conversations, and no emails and SMS messages then you have a problem," Alexander Ignor, a criminal law expert, told the Bild newspaper, adding that it could make it harder to secure prosecutions. The scandal will further weaken the position of Jorg Ziercke, the head of the BKA. The senior policeman has been criticised for the police handling of an investigation into the activities of the neo-Nazi National Socialist Underground, a three-person terrorist cell that murdered nine men of immigrant background and a policewoman between 2000 and 2006.