As Brigadier Stephen Saunders' killers are brought to justice, BBC News Online looks at his wife Heather's tireless fight for justice
Heather Saunders was awarded an OBE
On hearing of the first convictions on Monday morning, Mrs Saunders told BBC Breakfast she could not believe her fight was finally "coming to a head".
"I'm actually sitting here sort of shaking", she said.
The day after her husband's murder in 2000 Mrs Saunders emerged from the gates of the British Embassy in Athens to make an extraordinary appeal for witnesses.
"I only hope that the people that carried out this cowardly act on an unarmed man on his way to work will realise the total devastation that they have caused."
"Not only have they killed my husband, but they have now destroyed me and my entire family."
The couple, from Melbury Osmond, Dorset, had two daughters, Nicola, 16, and Catherine, 15.
Days later Mrs Saunders began handing out stickers to motorists in the Greek capital urging them to help police.
It was the beginning of a relentless pursuit for justice that was to consume her waking hours for the following three and half years.
Brig Saunders was shot four times in the chest as he drove from a northern suburb of Athens to the British Embassy on 8 June 2000.
Two men on a motorcycle rode up alongside his unmarked white Rover 800 in a traffic jam and opened fire at point blank range through the passenger window.
The helmeted killers then drove off at speed into the traffic, leaving their victim to bleed to death.
The defence attache, 52, was rushed to hospital but surgeons could not save him.
He had been on his way to join junior Defence Minister Baroness Symons, with whom he dined the night before, for a meeting with Greek ministers about British arms sales to the country.
The son of an Army officer, Brig Saunders had served in many of the world's trouble spots, including Berlin, Cyprus and Northern Ireland. He had been awarded the Queen's Commendation for Valuable Service.
He was buried with full military honours after a service at Salisbury Cathedral.
November 17, a Marxist and anti-Western group, which had carried out at least 23 other killings, claimed responsibility for the shooting.
In a ferociously worded communique, the group said the brigadier had been punished for his "instrumental role" in Nato's 78-day aerial bombardment of Yugoslavia during the Kosovo conflict.
Brigadier Saunders was en route to work when he was shot
Following Mrs Saunders' relentless pressure on the authorities in both countries, Jack Straw, then Home Secretary, visited the Greek Public Order Minister, Michalis Chryssohoidis, to discuss the case.
The Greek Government offered a £3m reward for information on the killers.
And British intelligence and Scotland Yard were brought in to help Greek police track down the terrorist group.
British officers undertook a detailed review of all Greek police files on November 17 attacks spanning 25 years, and put forward a number of recommendations for Greek police to consider.
Anti-terrorist squad and Special Branch officers continued to work closely with the Greek police, assisting them with investigative, forensic and other techniques.
In June 2001 the district attorney's office in Athens filed blanket murder charges against the "unknown perpetrators" responsible for the assassination so a full-time prosecutor and magistrate could be assigned to the case.
The breakthrough came a year later when a bomb being carried by 41-year-old Savas Xiros exploded prematurely, leaving him badly injured and in the hands of the authorities.
He was the first ever suspected November 17 member to be arrested.
Within months 19 suspected members of the group had been arrested and charged and Greek police had found the .45 calibre pistol allegedly used to kill Brig Saunders.
Three of the group - Mr Xiros, his brother Vassilis, 31, and 45-year-old Dimitris Koufodinas - were found guilty on Monday of Brig Saunders' murder.
November 17's leader, French-born academic Alexandros Giotopoulos, 59, was found guilty of planning the shooting of the British diplomat.
Mr Koufodinas' wife, Angeliki Sotiropoulou, 40, who was accused of being an accomplice to the murder, was acquitted due to lack of evidence.
In October 2002 Mrs Saunders filed a civil action allowing her to take part in the trial of the suspected November 17 members.
She told the Guardian newspaper: "I just want these people deprived of their freedom and taken away from their family and loved ones as I, my two daughters and my mother-in-law were taken away from ours."
Last December Mrs Saunders was awarded an OBE for her tireless fight for justice.
In March 2003 Greek prosecutors began the country's largest trial for decades by reading out more than 2,000 charges against the 19 alleged November 17 members - it took six hours.
The trial was held in a heavily-protected courtroom built inside Greece's main maximum security prison, just outside Athens.
Hundreds of witnesses were called to give evidence of alleged murders, bombings and robberies.