Toronto police Const. James Forcillo insists he didn't lose his cool during a fatal confrontation with Sammy Yatim, a knife-wielding teen, on a Toronto streetcar two years ago.

Forcillo was testifying in his own defence at his high-profile trial in Ontario Superior Court in Toronto on Monday.

Forcillo, 32, has pleaded not guilty to second-degree murder and attempted murder in the 2013 shooting of Yatim, who had caused a disturbance and was waving a knife inside the 505 Dundas streetcar when police arrived on the scene.

"You were the one who lost your cool, not him," Crown prosecutor Milan Rupic said during cross-examination. Rupic had earlier asserted that Yatim had his hands up when Forcillo yelled at him to drop the knife he was holding.

"I completely disagree," Forcillo replied.

Rupic told Forcillo he didn't see Yatim's hands up "in mock surrender" because "he mocked you, got under your skin. You didn't react well to being disrespected, you took it the wrong way. That's why you didn't see his left hand up."

Forcillo denied this, saying, "He did not mock me. At no point was I angry. The reason I didn't see his left hand is because I didn't see it."

Asked if it occurred to him that his partner Iris Fleckeisen might have been trying to de-escalate the confrontation by holstering her handgun, Forcillo replied, "No."

Rupic told the courtroom that seven seconds after holstering her gun, Fleckeisen asked Yatim in a calm voice if there was anyone else on the streetcar. The Crown then asked Forcillo if that interaction could have been the first step in resolving the crisis.

Forcillo agreed it might have but said Yatim wasn't interested in a conversation because he replied to Fleckeisen's question by calling the officers "pussies."

Last week, Forcillo spent two days testifying in the witness box as the defence aimed to prove he was doing what he was trained to do when he shot Yatim and that he had been acting in self-defence.

Forcillo's trial, now in its seventh week, continues at the Ontario Superior Court Tuesday. You can follow what's happening in the courtroom in our live blog below.