Andrea Varriale claims his partner Mario Cerciello Rega was slain in an unprovoked nighttime attack on July 26, 2019 after the officers, who were in plain clothes, approached the two Americans, who had earlier tried to buy drugs.
Varriale described to the Rome court how he desperately tried to stem the bleeding from Cerciello's wounds until an ambulance arrived, but “the blood was spurting out”.
Finnegan Lee Elder and Gabriel Natale-Hjorth allege they were attacked by the policemen from behind on a dark street in Rome, and defended themselves from what they believed to be dangerous drug dealers.
“We approached the pair from the front and we pulled out our badges, saying we were police,” Varriale told the court, according to Italian news agencies at the hearing, which was closed to most media due to coronavirus restrictions.
Elder, 20, has admitted to stabbing Cerciello several times with an eight-inch combat knife, but insists he did not know he was a police officer.
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.
“They had nothing in their hands. We just wanted to identify them. They immediately attacked us,” Varriale said.
“I was grabbed by Natale and we wrestled on the floor. At the same time I could hear Cerciello shouting 'Stop! Police!' His voice was breaking,” he said.
“The whole thing lasted just a few seconds. I let my aggressor go because I was alarmed by Cerciello's shouts. I looked up and I saw him standing, and he said 'they stabbed me', before collapsing on the ground.”
The court then heard the audio recording of the emergency call Varriale made, but the father of Cerciello's widow was taken ill as the call was played, and the judge adjourned the hearing until Thursday.
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A picture of the knife believed to have been used to kill policeman Mario Cerciello Rega. Photo: Filippo Monteforte/AFP
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.
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.
Varriale stuck by his story that he had been carrying his gun until August 9th, 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 was 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 the theft was revenge for the dealer having tried to rip them off. What they did not know was that the dealer was a police informant.
When they set up a meeting to swap the bag in return for money, the police turned up
While Varriale says he and Cerciello showed the Americans their badges, Cerciello's badge was never found, and in the chaotic aftermath of the stabbing, Varriale was not asked to produce his badge or his handcuffs.