ROME — A man who police allege introduced two U.S. teens to a Rome drug dealer and whose backpack was later stolen, setting off a chain of events that ended in the stabbing death of an Italian policeman, on Thursday said the Americans arrested for the officer's murder had threatened him.

Americans Gabriel Christian Natale-Hjorth, 18, and Finnegan Lee Elder, 19, were arrested on Friday in connection with the stabbing death of the officer Mario Cerciello Rega, 35. The attack allegedly occurred in Rome during a scuffle as Rega tried to retrieve a stolen backpack belonging to an Italian national, police said.

Authorities had said the backpack contained identification and the cellphone belonging to Sergio Brugiatelli. Police released audio recordings of Brugiatelli reporting the crime, saying the perpetrators had demanded 100 euro ($112) for the return of the bag.

Police also allege the Americans demanded a gram of cocaine.

On Thursday, Brugiatelli released a statement through his lawyer, saying he contacted police because he feared for himself and his family.

“When I called my cellphone number, whoever answered not only asked for money and drugs, they threatened me, saying that they knew where I live and that they would have come look for me," the statement said.

Brugiatelli added that there were keys to his home that he shares with his father, sister and nephew inside the bag. He said he was afraid the thieves could hurt his family.

Police have said a meeting was set up between the teens and two plainclothes Carabinieri paramilitary officers to recover the bag. Rega was unarmed, only carrying handcuffs, when he encountered the teens who were wearing hoods, officials said.

Police say the suspects ran away after stabbing Rega and punching the other officer. It took police less than 12 hours to arrest Natale-Hjorth and Elder at a hotel 260 feet from the crime scene, with the help of surveillance video.

Elder and Natale-Hjorth will remain in custody because of the severity of the allegations of both homicide and attempted extortion, a judge ruled earlier this week. Neither has been charged and they have not yet entered a plea.

Police have said the pair accused one another for the stabbing when separately interrogated, but added that Elder admitted to being the owner of a knife found in their hotel room.

Elder's family said earlier this week they planned to travel to Rome and were grateful the teen had been provided with medical care while in custody.

Natale-Hjorth's father Fabrizio Natale released a statement through his lawyer saying he had a "very emotional but also very hard" meeting with his son in prison on Wednesday.

"He is devastated by the Carabineire's death and I for one, as a father, painfully feel his family's grief," he said, adding he believes his son is innocent.

Claudio Lavanga reported from Rome and Linda Givetash from London.