An undercover Italian cop who was fatally stabbed in a scuffle with two American teens suffered wounds so deep that the base of the 7-inch blade left imprints on his skin, according to a new report.

Mario Cerciello Rega, 35, a deputy brigadier in the Carabinieri paramilitary police force, bled to death after being stabbed 11 times on the streets of Rome on July 26.

The officer’s wounds penetrated major organs, including both lungs, according to an autopsy report obtained by ABC News.

He had just returned to duty from his honeymoon with his wife, Rosa Maria Esilio, in his hometown of Somma Vesuviana six weeks before.

“The widow is devastated and in deep sorrow,” Esilio’s attorney, Massimo Ferrandino, told ABC News.

Finnegan Lee Elder, 19, and Gabriel Christian Natale-Hjorth, 18, who attended the same high school in Mill Valley north of San Francisco, were drunk and trying to score cocaine in Trastevere, a popular party spot, according to authorities.

They were enraged when they paid $100 for coke but got crushed-up aspirin, so they stole the dealer’s bag and cellphone and demanded $112 and a gram of cocaine to return the bag, police said.

But the dealer called cops, who set up a sting near the teens’ four-star Hotel Meridien Visconti near Rome’s Tiber River. A brawl broke out and Elder allegedly stabbed Cerciello Rega repeatedly.

The suspects fled but were tracked down at the hotel, where police recovered the knife in the room’s fake-tile ceiling.

Authorities said Elder confessed to stabbing the cop, but claimed it was in self-defense, and Natale-Hjorth admitted punching another officer at the scene.

The two remain jailed in Italy’s capital on suspicion of attempted extortion and aggravated murder.

Gen. Francesco Gargaro, commander of the Carabinieri in Rome, told reporters that Cerciello Rega had “forgotten his gun” that fateful night, but that there was still “no time” for the cops to react.

Cerciello Rega’s partner, Andrea Varriale, is now under investigation for failing to bring his service weapon when responding to the incident, according to prosecutors.

Since there were no frontal injuries on Cerciello Rega’s thorax and abdomen, the coroner concluded that he had been standing very close to the attacker, ABC News reported.

There also were no stabbing injuries on the officer’s body and only one wound that could be classified as defensive, caused by opposing an upper arm or stopping a blow, the report said.

Elder’s defense attorney claimed that the autopsy contradicts the allegation by police that the teens attacked the cops first.

“The autopsy stab wounds don’t support an immediate attack,” Craig Peters told San Francisco ABC station KGO-TV. “There’s no stab wounds on the front of Cerciello’s body.”

The attorney for Cerciello Rega’s wife said in a statement, “We will make our final evaluation when the investigation is over, we cannot rely on the press to acquire information that may not even correspond to the investigators’ findings.

“I only know that there is a person who was savagely killed with 11 stab wounds, we will see how this trial will end,” the attorney added. “We hope that it will start soon and, above all, will be speedy.”