Brandon Volpi, 18, was killed while he was trying to intervene in a fight over a cellphone, an assistant Crown attorney told court in Ottawa during the accused's second-degree murder trial on Tuesday.

Brandon Volpi, 18, died from his injuries after a stabbing outside a downtown Ottawa hotel early in the morning hours of June 7, 2014. (Photo courtesy of Brandon Volpi's family) During his opening statements in Superior Court, Michael Boyce told the jury that Volpi left an after-prom party at Les Suites Hotel in downtown Ottawa on June 7, 2014, and died 90 minutes later of a knife wound to the heart.

It happened around 3:30 a.m. outside the hotel on Besserer Street, where students from three Catholic high schools were gathered for an after-prom party.

Boyce told the court Devontay Hackett, who was 18 at the time and is now 21, had been fighting with another student over a missing cellphone.

The student said he felt threatened and asked Volpi for help as Volpi and his friends were walking by in the hotel lobby, Boyce said. The students all went outside the hotel, where Hackett and Volpi came into contact with each other and Hackett pulled out a knife, Boyce told the court.

Stab wound to heart fatal blow, court told

Volpi had a 17-centimetre stab wound to the neck, close to a jugular vein, and suffered slashes to his face, elbow and underarm, Boyce said. A 10-centimetre-deep penetrating stab wound through Volpe's rib cage and into his heart was the injury that killed him, Boyce told the court.

Boyce implored the eight men and four women on the jury to "look at the number, the nature and the location of the wounds on Volpi's body."

The Crown said video evidence shows Hackett running away into an alley separating Les Suites Hotel from a neighbouring hotel after the stabbing.

This cellphone and security footage shows a fatal prom night fight outside a downtown Ottawa hotel in June 2014. It was shown at the murder trial of Devontay Hackett, who accused of killing Brandon Volpi. 0:46

Hackett was arrested nearly a month later in Toronto on a Canada-wide warrant and charged with second-degree murder.

He had attended St. Pius X High School while Volpi was a student at St. Patrick's High School.

Videos show scuffle

Ottawa police released this image of Devontay Hackett, accused of second-degree murder, in 2014. (Ottawa police) The Crown's first witness, Ottawa police civilian forensic imaging expert Michael Ross, took the court through videos from security cameras in the lobby of the hotel, a camera at a neighbouring hotel and two mobile phones.

While the lobby security footage focused on the lead-up to the incident, two hotel guests captured the physical altercation outside with their phones, one from the third-floor balcony and another from the 10th floor of the hotel.

Ross told the court he's viewed the blurry, grainy videos 50 times.

The third floor video showed one man dressed in black, identified by Ross as Volpi, fighting another man dressed in white, identified by Ross as Hackett.

Accused appears to lunge at Volpi: witness

The two men are outside surrounded by three others, while about 15 people stand on the street screaming and swearing as they watch the fight unfold.

Ross slowed the video down frame by frame to show the court that Hackett seemed to lunge at Volpi with his right arm extended before pulling back.

In another frame, Ross pointed to Hackett making a sweeping motion with his right arm at Volpi. Ross told the Crown Hackett had what appears to be a "light-coloured object in his right hand."

Ross then pointed to the man identified as Hackett running away from the scene while security guards come to Volpi's aid.

The trial is expected to continue Wednesday.