KITCHENER -- WARNING: Some details may be disturbing to readers.

An Elmira teen is on trial for first degree murder in the death of his mother.

Through his lawyer, he pleaded guilty to second degree murder but not guilty to first degree murder in her death.

Since the teen has been charged as a youth, the trial is judge alone at the Waterloo Region Courthouse. The identity of the accused is protected under the Youth Criminal Justice Act.

The court heard on Monday that the victim was stabbed to death at the end of November 2017. Her body was discovered weeks later.

A friend of the victim was in the courtroom for day one of the trial. She tells CTV Kitchener that the victim’s kids were her world, but she was also a good friend, loved sister, daughter, and aunt.

The first witness to testify was the victim’s brother. He told the judge that he last saw his sister at a family party a few days before she died.

At the party they discussed her son’s grades slipping and ways to bring them back up, like taking away video games.

He testified that he went to her home on Christmas Day in 2017 when she didn’t respond to phone calls or text messages, opened the door, and there was a “terrible smell of spoiled meat.”

Court saw photos of a large pile of furniture blocking the front door.

The man testified that he had to enter through the back door and saw muddy footprints all over when he finally got in.

He adds that when he went to his sister’s room he realized it wasn’t mud, but blood.

A forensic officer testified he counted 162 bloody foot impressions in the home.

The victim’s brother says his sister’s blood was over the covers, walls, and at the end of the hallway was a blanket and a body.

The court heard that the teen was arrested a few days after the victim’s body was discovered.

The Crown alleges there will be evidence presented that was found on the teen’s computer suggesting he is guilty of first degree murder. They have also notified the judge that they will be applying for an order that he be sentenced as an adult.