The Italian police officer who was fatally stabbed in an altercation with two American teenagers was unarmed at the time of his death, police and prosecutors said Tuesday.

Gabriel Christian Natale-Hjorth, 18, and Finnegan Lee Elder, 19, both from Mill Valley, California, were arrested and detained by police in Rome on Friday on allegations of homicide and attempted extortion.

On Monday, a judge ordered that the pair remain in custody because of the severity of the allegations.

At a press conference Tuesday, police and prosecutors said they were still investigating the events that led up to the stabbing of Carabinieri Mario Cerciello Rega, 35, and released an image of the alleged murder weapon.

Hundreds of mourners gathered in Rome to say goodbye to Rega on Monday.

The teens were provided with lawyers and translators, even though one of them said he speaks Italian, prosecutors and police said in a press conference Tuesday morning, when they described their investigation in detail.

A photo of the knife Italian police say American Finnegan Lee Elder used to stab a police officer in Rome. Italian police

Italian officials said that they were also investigating why Natale-Hjorth had been illegally blindfolded after he was apprehended. Italian newspapers published a photo Sunday of the teen with what appeared to be a scarf covering his eyes and his hands handcuffed behind his back as he sat in a chair at a police station.

Police said that Natale-Hjorth and Elder had a violent encounter with two plainclothes Carabinieri after they stole a backpack from an Italian national, identified as Sergio Brugiatelli. Police claim they demanded money and a gram of cocaine in exchange for its return.

Brugiatelli set up a meeting with the teens and two plainclothes officers went to the meeting, where they encountered the teens who were wearing hoods, the officials said.

Rega had forgotten his gun and had only handcuffs on him, officials said.

The officials said that Elder explained that he brought the knife with him to the meeting because he was “afraid something could go wrong.” He then used the knife, which he had brought with him to Italy from the United States, because he was afraid, police said.

Elder also admitted to taking pharmaceuticals, and drinking alcohol before the incident, officials said. Prosecutors said Monday that Elder told them that he reacted by stabbing Rega because he felt like he had been strangled. Prosecutors said earlier that CCTV and witnesses weren’t able to confirm this.

After the stabbing, the teens fled the scene. It took police less than 12 hours to find them, with the help of CCTV. Their hotel is located around 260 feet from where the stabbing took place.

Police said they found what they believe is the knife used in the attack hidden in the walls of the teen’s hotel room. Given the size of the knife, they believe it was impossible that Natale-Hjorth didn’t know that Elder had it on him.

Elder’s family, who are planning to travel to Rome, said Monday that a U.S. government official has briefly met with the jailed teen and that they were "grateful that he has been provided medical care."