Greece launched a hunt yesterday to find how a parcel bomb that ripped through the police ministry, killing the minister's own security chief, was smuggled into the heavily-guarded building.
Police said it was too early to blame any specific group for the attack on Thursday evening that killed the close aide of Citizens' Protection Minister Michalis Chryssohoidis and damaged offices on the ministry's seventh floor.
But serious questions have arisen regarding security at the building which is the heart of police operations in Greece and is supposed to be one of the country's most heavily guarded sites.
The Greek national intelligence service (EYP) is also based there.
The bomb was hidden in a cardboard box and consisted of half a kilo (one pound) of gunpowder and ammonium nitrate, a police source said.
A bomb disposal unit also found the remains of a battery and a hook that was likely used to activate the explosives when the box was opened, the source added.
The parcel was apparently addressed to Mr Chryssohoidis, who had recently married, but a police source said it was impossible to confirm for the moment what was written on the slip.
The victim George Vassilakis, 52, was a close associate of the minister for the past decade and was tasked with inspecting Mr Chryssohoidis' correspondence. The minister, who has led a crackdown on far-left groups responsible for other attacks, was just a few metres (yards) away when the bomb went off and was unhurt.
Greek Prime Minister George Papandreou told Parliament yesterday that the perpetrators of the "heinous terrorist act" would not win.
"Yesterday we witnessed an incident of blind and inhuman violence," he said.
"A family man fell victim to a heinous terrorist act."
"The murderers should know that they will fail because they have the state and all of society against them. Our society cannot be terrorised," the Prime Minister added. The explosion happened as the country battles a major debt crisis. The Socialist government's austerity programme has provoked widespread strikes and protests.
"It is nearly impossible for someone carrying a bomb to get into the ministry, but to get a packet in is easier," said police union official Vassilisi Doumas, speaking on Flash radio.
He said the booby-trapped package could have been carried into the building by a member of staff, a possibility also raised by Greek media.
Police spokesman Thanassis Kokkalakis admitted there could have been "negligence" by the building's security. He told Sky radio there was no specialist bomb detecting equipment at the entrance.