An Italian police commander on Tuesday revealed that a plainclothes Carabinieri police officer had forgotten his gun on the night that he was fatally stabbed in a confrontation with two American teenagers but insisted there would have been no time to draw a weapon anyway.

From left, Carabinieri Colonel Lorenzo D'Aloia, prosecutors Nunzia D'Elia, and Michele Prestipino, and Carabinieri General Francesco Gargano arrive to a press conference about the investigation on the murder of Carabinieri's officer Mario Cerciello Rega in Rome, Tuesday, July 30, 2019. (Photos: AP)

At a news conference, Carabinieri Gen. Francesco Gargaro defended the police response early Friday, providing the first details about the clash in which Deputy Brigadier Mario Cerciello Rega, 35, was knifed 11 times.

He said Cerciello Riga and his partner, Andrea Varriale, were assigned to respond to an extortion attempt, allegedly made by the teens, to get money and cocaine in return for stealing a knapsack in the wake of a failed drug deal.

Finnegan Lee Elder, 19, and Gabriel Christian Natale-Hjorth, 18, both from California, were detained early Friday in the slaying of Cerciello Rega. The next day their jailing in Rome was upheld by a judge, who said there were "grave" indications they were responsible for the death.

According to the judge's ruling, Elder and Natale-Hjorth had paid for cocaine from a drug dealer in Rome's Trastevere neighborhood but the deal didn't end successfully as police approached. Investigators said the two then snatched the knapsack of an Italian man who had put them in contact with a pusher to buy cocaine.

Police say when the man, Sergio Brugiatelli, called his own cellphone, which was in the snatched bag, the teens told him they'd give the bag back in exchange for 100 euros ($112) and a gram of cocaine. Investigators say after the man reported the extortion attempt to police, an appointment with the teens was set up and Cerciello Rega and Varriale were sent to the rendezvous point.

Gargaro told reporters Tuesday that the officers in plainclothes identified themselves as Carabinieri as they approached, but were immediately attacked by the Americans wearing hoodies.

Carabinieri Colonel Lorenzo D'Aloia shows a picture of the knife used to stab Carabinieri's officer Mario Cerciello Rega, during a press conference in Rome, Tuesday, July 30, 2019. 

Judge Chiara Gallo in her ruling Saturday said the teens told interrogators they weren't aware that the men were Carabinieri, but she quoted Varriale as telling investigators they announced they were Carabinieri and showed their badges, and then were immediately attacked.

Cerciello Rega was stabbed 11 times and died about 45 minutes later at a hospital, Gargaro said.

Asked why Cerciello Rega didn't pull his gun, Gargaro said the officer had "forgotten" his gun that night after being called into service on a day off. It was not immediately unclear if the slain officer's superiors knew he had no gun when he was sent out.

"In any case, there was no time to use it," Gargaro insisted, claiming the two officers were immediately attacked by the teens after announcing they were police.

Varriale did have his gun, but after Natale-Hjorth, who had been attacking him, punching and scratching, ran off, the officer turned his attention to his wounded partner, Gargaro said.

The general also stressed that under Italian law it is illegal to fire at a fleeing suspect.

"There was no possibility of using the weapons," he said.

Police who traced the Americans to their upscale hotel room say a search found the alleged weapon, an 18-centimeter (7-inch) military-style attack knife hidden inside the room's drop ceiling.

Gargano said Tuesday that Elder said he had brought the knife with him on his trip from the United States a few days earlier.

During his interrogation, Elder told authorities he stabbed Cerciello Rega because he feared he was being strangled, the judge wrote, noting the teen didn't have any marks on his neck.

She also cited contradictions in the teens' accounts: Elder told investigators that Natale-Hjorth hid the knife in the ceiling while Natale-Hjorth told investigators he wasn't aware of the stabbing until Elder woke him hours later in their hotel room and told them he had "used a knife" and then washed it.