Police investigating the murder of three taxi drivers have asked potential witnesses to step forward. The murders all happened on the same day of the week and according to unconfirmed sources all three drivers were shot in the back of the head with the same weapon. In each case the killer is believed to have taken a taxi from the centre of Prague to the outskirts where he committed the murders. The case has spread fear among Prague taxi drivers some of whom are now armed. Others refuse to take passengers off the street only responding to calls from an operator.