premise: Fourteen men accused of belonging to a radical Muslim terrorist group, including the convicted killer of filmmaker Theo van Gogh, go on trial Monday at Amsterdam's high security court.
  The murder of outspoken Islam critic Van Gogh and the subsequent arrests of the alleged members of the terror ring dubbed the Hofstad group have heightened fears that the country is a target for Islamic terrorists.
  However, prosecutors have already suffered setbacks, being forced to drop charges the group was specifically planning to kill several Dutch politicians, and losing a similar case against another accused terrorist.
  Prosecutor Koos Plooy has admitted that they have insufficient evidence to proceed with charges the group was planning specific attacks, but said they were definitely heading that way.
  The prosecution alleges that 27-year-old Mohammed Bouyeri, convicted to life in prison for murdering Van Gogh, was a leading member of the Hofstad group.
   What caused heightened fears that the country is a terrorist target?
hypothesis: murder of outspoken Islam critic Van Gogh and the subsequent arrests