Friday was a day of transition at the Michael Schweitzer murder trial, as the Crown’s final witness concluded his testimony and the defence was able to call its first witness.

The day began as Thursday ended, with Const. Christian St-Amour of the Ontario Provincial Police on the stand.

St-Amour was the first police officer to respond to the Milverton home where 17-year-old Nicole Wagler was shot and killed on Dec. 4, 2012.

Tyler Baker, who lived in the home with Schweitzer, was also shot and was seriously hurt.

Schweitzer has pleaded not guilty to murder and attempted murder in connection with the shootings.

His lawyers have suggested that Baker could have killed Wagler, then turned the gun on himself.

Cross-examination of St-Amour was focused on the phrase ‘What have I done?’, which the OPP officer said he heard Schweiter utter more than 10 times as he sat in the back of a police cruiser.

Defence lawyers argued that St-Amour was too far from the car to clearly hear and understand what Schweitzer was saying inside, even with a window down.

St-Amour responded that it was difficult to hear specific words over the sound of Schweitzer banging his head against the Plexiglas divider as he spoke, but he did hear the phrase several times.

After the cross-examination was complete, Catherine Rivers was called to the stand as the trial’s first witness for the defence.

Rivers, Schweitzer’s stepmother, also showed up at the Edward Street home minutes after the 911 call.

Jurors heard that she arrived at the home with Schweitzer and his father, as Schweitzer had gone to his father’s house after the shooting occurred.

Once at the home, she gave first aid to Baker, who had suffered serious head injuries in the shooting.

Jurors heard a recording of Rivers’ conversation with 911 dispatchers. At one point, she said that “the person that did this is in the vehicle out in the driveway.”

Rivers told the court that when she made that comment, she was in the house along with Schweitzer’s father, Baker and another person – meaning Wagler.

She explained the comment Friday as her saying whatever came to her mind, not as her suspecting Schweitzer of being the shooter.