ROME (AP) — An Italian police officer testified Wednesday at the murder trial of two Americans about trying in vain to stop blood pouring out like a “fountain” from his partner who was fatally stabbed last summer in Rome.

The two young men from California were in Italy's capital as tourists a year ago, and are charged in the killing of Carabinieri Vice Brigadier Mario Cerciello on a street near their hotel on July 26, 2019.

The Americans, Finnegan Lee Elder, now 20, and Gabriel Natale-Hjorth, now 19, said in pretrial questioning that they mistook Cerciello and his partner as criminals trying to attack them and that they scuffled with the Italians to defend themselves.

Prosecutors allege that Elder stabbed Cerciello 11 times and that Natale-Hjorth hid the murder weapon, a military-style attack knife that Elder allegedly brought with him in a suitcase from the United States. Under Italian law, defendants having a role in the case can also be charged with murder.

The confrontation followed an alleged attempt by the tourists to buy cocaine earlier in the evening in a Rome nightlife district. After allegedly paying for the drug, the Americans realized they were swindled and didn't receive it.

Angry they received no cocaine, the Americans snatched a backpack with a cellphone inside that belonged to the drug dealer's go-between, the prosecution contends.

The backpack's owner told police that when he called his own phone, one of the Americans answered and demanded money and cocaine in exchange for returning the bag.

Cerciello’s partner, Andrea Varriale, testified that the two officers were dispatched on a plainclothes pre-dawn mission to retrieve the bag from the alleged extortionists. He said he pulled out his badge and yelled, “Carabiniere’’ to identify himself as a police office.

Varriale said he was wrestled to the ground by one of the defendants, whom prosecutors say was Natale-Hjorth, while the other defendant struggled with Cerciello.

At one point, “I looked to the left, Mario was on his feet, swaying. ‘They stabbed me, they stabbed me,’" Varriale said his partner called out. “I saw the blood coming out like a fountain to the ground."

Natale-Hjorth has told investigators he didn’t know his friend brought a knife to the rendezvous.

Wednesday’s hearing was abruptly ended for the day after Cerciello’s father-in-law collapsed in the courtroom and was taken to a hospital.