The trial of a US soldier charged with the murder of an Italian intelligence agent in Iraq in March 2005 has begun in a Rome court.
Mr Calipari (pictured) was shot after rescuing a hostage journalist
The soldier, Mario Lozano of the 69th Infantry Regiment, is not attending the trial, but in Italy the defendant can be tried in absentia.
The agent, Nicola Calipari, was shot dead on his way to Baghdad airport.
Mr Lozano is charged with murder and two counts of attempted murder. He denies the charges.
He was escorting Giuliana Sgrena, an Italian journalist who had just been freed by kidnappers. She was wounded in the incident, along with an Italian secret agent - Andrea Carpani - who was driving the car.
Soon after the trial opened the judge adjourned it for technical reasons until 14 May.
US soldiers opened fire as the Italians' car approached a roadblock.
US military: Car approaches checkpoint at high speed
Troops attempt to tell driver to stop with arm signals, lights and warning shots
Soldiers shoot into engine
Italian government: No warning signs to motorists about impending checkpoint
Car not speeding and did not accelerate after warning shots
Proper inquiry impossible because vehicles removed and army logs destroyed just after shooting
Calipari, who shielded the journalist during the shooting, was hailed a hero at home, awarded Italy's top bravery award and given a state funeral attended by tens of thousands.
Franco Coppi, representing Calipari's widow, said the fact the American was not in court did not jeopardise the case.
"His absence is his own choice," he told reporters. "It does not represent an obstacle to ascertaining the truth. We are absolutely serene. The evidence gathered is indisputable."
Mr Lozano's lawyer, Alberto Biffani, said his client had no formal knowledge of the trial proceedings.
Lawyer Franco Coppi called that statement "an insult" and accused Mr Lozano of "a form of arrogance".
Mr Lozano's defence team say the incident was caused by the Italians' "lack of caution", adding that they should have had a military escort.
Italy and the US drew very different conclusions over what had happened.
The US military said the vehicle was travelling too fast, alarming soldiers, who feared it was an insurgent attack.
Italian officials claimed the car was travelling at normal speed and accused the US military of failing to signal there was a checkpoint.
Mario Lozano, both countries agree, fired the fatal shots.
He has told newspapers he had little choice but to open fire.
Explaining the rules of an engagement at a roadblock, he said: "You have a warning line, you have a danger line, and you have a kill line."
The soldier said he flashed a spotlight at the vehicle as it approached, then fired warning shots, and then fired at the engine.