The trial for a Winnipeg mother accused of manslaughter in the death of her infant son began in Winnipeg this week.

Michele Camire is accused of manslaughter in connection with the 2004 death of three-and-a-half-month-old Michael Helgason, who died of blunt force trauma to the head.

Winnipeg firefighter Bradley Mazor, who was called to Camire's townhouse on Rothesay Street on the day of the incident, testified in provincial court Monday that as he administered CPR to Helgason, Camire said the baby had been thrown down into its bassinette out of frustration.

Similar comments were made by Camire to 911 dispatchers. During the audio recording, played in court, Camire is heard saying, "My baby was crying earlier today. I got mad and frustrated I slammed him down when I put him down and now he's dead."

She also is heard saying, "Oh my God, I can't believe I did this."

A Manitoba medical examiner determined the cause of death was a brain injury. Susan Phillips also found during her autopsy that Helgason — one of triplet boys — also suffered a fractured skull.

Court has also heard evidence from a forensic identification officer with the Winnipeg Police Service, who described the process of photographing the crime scene, and testimony from family support agencies who have described the types of supports that were available to Camire, who has pleaded not guilty.

The trial, being heard by a jury of seven men and five women, is set to last until Friday.