An Italian policeman is to take the stand Wednesday in the trial of two US students accused of the murder of his partner during a failed drug bust last year.
Andrea Varriale claims his colleague Mario Cerciello Rega was slain in an unprovoked nighttime attack on July 26 after the officers, who were in plain clothes, approached the Americans, who had earlier tried to buy drugs.
Finnegan Lee Elder and Gabriel Natale-Hjorth allege they were attacked by the policemen on a dark street in Rome, and defended themselves from what they believed to be dangerous drug dealers.
Elder, 20, has admitted to stabbing Cerciello several times with an eight-inch combat knife, but insists he did not know he was a cop.
The San Francisco native, who was 19 at the time of the incident, says Cerciello attacked him from behind, while Varriale wrestled with Natale-Hjorth, then 18.
The two Americans face life sentences if found guilty of knowingly killing a police officer.
"He was an exemplary man, the best," Cerciello's brother Paolo told ANSA news agency in a rare interview last week.
"My father died 11 years ago and he (Mario) took his place. He loved his job, the police, his family, and helping people."
Natale-Hjorth initially told investigators he had not been involved, but his fingerprints were found on a ceiling panel in the hotel room where the students had hidden the knife.
Under Italian law, anyone who participates even indirectly in a murder can face homicide charges.
Gun, badge, cuffs
The defence says lies told by Varriale in the immediate aftermath of the stabbing -- such as whether or not the policemen were armed, as they should have been while on duty -- seriously undermine his credibility as a witness.
The day after the Americans were arrested, a photograph was leaked to the press showing Natale-Hjorth illegally blindfolded and handcuffed at the Rome barracks where he had been taken for questioning.
Varriale admitted he had not only been present, he had taken the photograph and had filmed the scene as well.
He would stick by his story that he had been carrying his gun until August 9, when he confessed that not only did he not have his gun on him, but that he had conspired with a superior officer to lie about it.
The defence is expected to ask Varriale why he and Cerciello left their designated patrol area to track down the US students, without informing central command.
The Americans had earlier that night stolen the bag of a man who had introduced them to a drug dealer.
They say it was revenge for the dealer having tried to rip them off. What they did not know was that the dealer was also a police informant. When they set up a meeting to swap the bag in return for money, the police turned up instead.
Varriale says he and Cerciello showed the Americans their badges. But Cerciello's badge was never found, and in the chaotic aftermath of the stabbing Varriale was not asked to produce his, or his handcuffs.