A Hamilton courtroom heard a chilling testimony on Tuesday from the brother of a teenager who was stabbed to death by his cousin at a family function last year.

13-year-old Cain Bistoyong testified that he saw his older cousin Laureano Bistoyong pick up a kitchen knife and stab his brother Mark in the chest.

Mark Bistoyong, who was just 16 at the time of his death, has been described by friends and family as a loving, outgoing and charismatic young man who was “athletic and full of life.”

“Mark was always a free spirit, always willing to help anybody,” Elizabeth Clannon, a family friend, recalled of him. “As long as everyone was happy, Mark was happy.”

Last year, a shocking act of violence took the beloved teenager’s life.

READ MORE: Man, 22, charged after fatally stabbing cousin at Hamilton Mountain family gathering

Bistoyong was stabbed to death by his older cousin, Laureano Bistoyong, at a family function — after playing a basketball game that several witnesses say was “physical.”

“I think beyond shocked is how I would define it. It’s something that happens to someone else’s family, not someone that you know or spend time with,” Jen Pate, another family friend, said.

The victim’s youngest brother, Cain Bistoyong, took the stand on Tuesday and said that he was sitting with his brothers at the party when he saw his cousin grab a knife in the kitchen.

Cain said he didn’t think anything of it until Laureano walked over to Mark, bent over and stabbed him in the chest. Then Cain said that Laureano took off through the back door.

Hamilton police officer Joshua Smith also testified on Tuesday and told the court that when he arrived at the house that night the scene was “chaotic” and “upsetting.”

He said he saw the victim, Mark Bistoyong, lying on the living room floor, then said he went out to the backyard, where he found three knives lying in the grass and in the bushes.

The victim’s family members and friends filled the courtroom and said Mark Bistoyong and his family were tightly knit, making what happened even harder to believe.

“No matter the circumstances, this not deserve to happen, it shouldn’t have happened,” Nicole Grehan, another close family friend told CHCH News. “I hope we get justice for him.”

Two other cousins who were at the party that day also took the stand and said the basketball game that was played at a court near the house the night of the stabbing got physical, with pushing and shoving between cousins — but both witnesses insisted that everyone was being rough and everyone agreed to play that way.

The defence attorney, however, suggested that the game got more heated than intended.

Laureano Bistoyong has been charged with second-degree murder. His trial will resume on Wednesday.