​A forensic video technician testified under cross-examination that he could not see any sign of a knife in footage from a prom night fight in which an Ottawa teen was fatally stabbed.

Devontay Hackett, who was 18 at the time and is now 21, is on trial for second-degree murder in the June 2014 stabbing death of 18-year-old Brandon Volpi.

Volpi died after a brawl outside an after-prom party at Les Suites Hotel in downtown Ottawa.

In an agreed statement of facts, the defence does not contest the Crown's position that Hackett is seen in videos fighting with Volpi.

But Hackett's lawyer, Joseph Addelman, took issue with what the video actually showed.

​On Tuesday, Mike Ross, a police civilian forensic imaging expert, walked the court through grainy mobile phone videos of the fight from the third-floor balcony of the hotel.

Ross had slowed the video down frame by frame and described a "light-coloured object" he said could be seen in Hackett's hand right hand just seconds before he and Brandon Volpi started fighting.

Addelman questions evidence of knife

During cross-examination on Wednesday, Addelman walked Ross through the video again, and asked the Crown witness if the object he described in Hacket's right hand is a knife. Ross replied "no, nothing is that visible."

Ross said he's watched the video 50 times but conceded the video goes in and out of focus during the fight.

Addelman pointed to a frame in the video where he said it appears Hackett punches a man next to Volpi because of the way the man's head snaps sideways.

Given that, Addelman asked Ross if Hackett's actions in that frame are inconsistent with him having a knife in his hand. Ross replied, "Yes."

Addelman also asked Ross if he had been trained to identify body movements on video, such as punches and blocks, and Ross said he had no such training.

"So you're in the same position as the rest of us who watched the video," said Addelman.

"That is correct," said Ross.

The defence cross-examination of Ross is expected to continue on Thursday.

On Wednesday the Crown also submitted a series of short clips from City of Ottawa traffic cameras and University of Ottawa security footage, which appear to show two people walking away from the area near Les Suites Hotel and through the university campus.

Died of knife wound to heart

During his opening statements in Superior Court on Tuesday, assistant Crown attorney Michael Boyce told the jury that Volpi left the after-prom party on June 7, 2014, and died 90 minutes later of a knife wound to the heart.

Devontay Hackett Canada-wide warrant suspect Brandon Volpi homicide

Ottawa police released this image of Devontay Hackett, accused of second-degree murder, in 2014. (Ottawa police)

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

Boyce told the court Hackett 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.

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 said.

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."