American teenager Daniel Petric is currently on trial for the murder of his mother, and the attempted murder of his father, after they told him he wasn't allowed to play Halo 3.

The 17-year-old, who was 16 at the time, allegedly snuck out of his bedroom window in September 2007 to purchase the game against his father's orders.

When his parents later caught him playing the game, they took it from him and secured it in a lockbox, where a 9mm handgun was also kept.

It was around a month later, on 20 October 2007, that Daniel used his father's key against his knowledge to open the lockbox to retrieve the game, and also the gun. He then turned the gun on his parents, killing his mother and severely injuring his father. While his father lay wounded, Daniel tried to place the gun in his hand before fleeing when his sister and her husband arrived at the house. He took the game with him.

His father testified that Daniel came up behind him and his wife asking them to close their eyes as he had a "surprise" for them.

Petric, 45, said he "expected a pleasant surprise" and closed his eyes, but felt his head go numb. He said it was only after he realised blood was pouring from his head that he noticed his wife, Susan Petric, 43, was lying dead having been shot in the head, arms and chest.

Petric added his son shoved the gun into his hand saying, "Hey Dad, here's your gun. Take it".

He then heard his daughter and her husband arrive and Daniel telling them they couldn't come inside because their parents had had a "big argument".

However, Heidi and Andrew Archer, testified they heard a moan and forced their way in to find the horrible scene. Heidi called 911 immediately, and Daniel fled.

Apparently the whole family have forgiven him and want him home, saying they cannot heal until they are all together.

His defence says he was under a lot of stress at the time of the incident following a snowboarding accident that left him with severe spinal damage.

He was homebound for a year and it was during this time of inactivity that Daniel supposedly became hooked on TV and video games, the Halo series in particular.

His father, a minister at a local church, had banned the games, saying that were too violent and sexually explicit.

Daniel is not facing the death penalty due to his age. The case continues.