PICTURED: Aspiring actor, 33, shot dead by California highway patrol officer during brawl on 105 Freeway - as it's revealed he was living homeless in LA after mental health breakdown

The family of an aspiring actor shot and killed by California highway patrol are demanding answers after video showed the 33-year-old being shot on three times while lying on the ground.

Jesse Dominguez died on Sunday after police were called to reports of a man wandering erratically along 105 Freeway in the Los Angeles district of Watts. Dominguez was staying at a shelter near the road.

Video of the incident shows Dominguez tussling with the highway patrol officer on the ground.

Dominguez carried a Taser for his own safety inside the homeless shelter, his family told The Los Angeles Times.

The two men wrestle on the ground, and the officer then draws his gun and shoots Dominguez dead.

'In fear for his safety, the officer fired his service weapon, striking the pedestrian,' said California Highway Patrol in a statement.

The California Justice Department is now investigating.

Dominguez's family said his killing was unjustified, describing it as pure 'police brutality'.

'I've pretty much 'backed the blue' in a lot of circumstances,' said Akasha Dominguez, his stepmother.

'There have been issues where [police] used excessive force. But I've never been on the other end.

'Now I have a completely different stance. This is absolutely police brutality.'

She said she found it obvious that her stepson was mentally ill, or suffering some sort of breakdown.

'I don't know why the officer thought to engage,' she said.

'If someone is walking on the freeway, something is not right. They're either in mental health crisis or something else is happening.

'He was not trying to hurt anybody. Why did he have to use that type of force? After [the officer] had already discharged his firearm once, why did he stand up and then do it again and again and again?'

His sister, Michele Dominguez, agreed that the response was excessive.

'I don't know when using deadly force became the first thing cops do in this situation,' she said.

One law enforcement analyst told the paper he thought the highway patrol officer's actions could be justified, but it was hard to judge from the short video clip.

'It is hard to diagnose without knowing what the officer saw, experienced and interpreted was happening,' said Travis Norton, who runs the California Association of Tactical Officers After Action Review.

'All I see is a very short scuffle. I see the suspect point something that appears to look like some sort of weapon.

'From the video, without knowing anything else about it, the use of deadly force appears appropriate.'

But another analyst agreed with the Dominguez family that the officer's actions seemed excessive.

Ed Obayashi, a police shootings expert who investigates on behalf of several California law enforcement agencies, said an obvious question was why the officer was alone, without backup.

He said investigators will ask the officer: 'Why did you shoot him while he was on the ground? You separated yourself from the individual; why was he still a threat to you?'

The family told The LA Times that Dominguez, who was bipolar, was 'a softie', who desperately wanted to be an actor or singer, but never got any roles.

His father, also Jesse Dominguez, 55, said that his son worked as a waiter to try and make ends meet while auditioning, and refused their offers of help.

'We just feel terrible that L.A. just robbed him,' he said.

'The Hollywood scene sucked him in to wanting to be that persona. No matter how hard we tried to get him to do other jobs or seek formal education, that's what he wanted to do.

'We weren't going to crush his dreams.'