An Italian university student allegedly burned alive by her jealous ex-boyfriend could have been saved had her desperate screams for help not been ignored by passing motorists, police said. Sara Di Pietrantonio, 22, was killed on the outskirts of Rome on Sunday (29 May) in what one investigator described as the most atrocious crime he'd ever seen in his career.

Her alleged attacker, former partner Vincenzo Paduano, 27, is said to have rammed her car and set it alight, before then chasing her about 100 metres down the road.

Police said Paduano went on to douse his victim in alcohol and set fire to her face with a cigarette lighter.

"I can say that in 25 years in this work I have never seen something so atrocious," said Luigi Silipo, the lead police official in the investigation.

Prosecutor Maria Monteleone said Paduano, who had been in a two-year relationship with the victim, was being held on suspicion of premeditated murder. He initially denied the killing but confessed after eight hours of interrogation, Silipo told reporters.

The attack came after Paduano "didn't accept being abandoned" by Di Pietrantonio, Monteleone said, adding that after he was dumped, he "organised [and] planned the aggression".

Police said the events of that day had seen the suspect leave his job as a security guard at about 3am and wait outside the home of Di Pietrantonio's current boyfriend. He then allegedly followed her as she left by car, eventually forcing her to the side of the road.

"He got into her car, and after an argument, doused the car with a small bottle of alcohol, and doused Sara, too," Silipo said. "She ran out, he torched the car, caught up with her, and after about 100 meters" set her ablaze, leaving her to die "in an atrocious manner", the police official said.

The young woman's charred body was found by firefighters at about dawn on Sunday close to her burning car in Via della Magliana, south west Rome. Paduano had returned to work after the murder, prosecutors said.

Partial CCTV footage of the event saw at least two cars pass by while the woman screamed for help, authorities said. Monteleone appealed for citizens "not to look the other way" when women are in danger, saying the victim's life could have been saved had someone stopped to help.

She also encouraged women "not to keep hidden any threatening behaviour by those who insist they love you".