"Justice Secretary Jack Straw apologised to the victims' families and a senior probation officer resigned over the blunders that left Sonnex free to kill.
But Guy Bonomo, the father of murdered Laurent, called for a prosecution, saying every official who allowed Dano Sonnex to remain on licence - even after his parole was revoked - should defend their actions in court.
Speaking in French after a press conference at Scotland Yard, he said he and the other parents had been 'failed' by Britain and its justice system.
He said: 'Sonnex should have been back in prison on June 13th, but he was not. He was not arrested until it was too late.
'I think that the people in the justice system who allowed him out on licence should be prosecuted.
'I think that every person concerned who had something to do with this should be in front of a court."