A Sydney mother is planning civil action against the New South Wales Police for the wrongful arrest of her daughter during a night out three years ago.

Melissa Dunn was arrested and charged in January 2012. A magistrate later said the police had used an "inordinate amount of force" during the arrest.

She was found not guilty of resisting and hindering police.

Three days after the trial ended in August 2012, the 17-year-old Aboriginal girl committed suicide.

The ABC's 7.30 program has obtained the CCTV footage of the arrest on George Street in Sydney.

In the footage, Melissa is chased and tackled to the ground by a police officer. She is then dragged in a headlock to the police van. She struggles, falls and is knocked unconscious when she hits her head on the gutter.

The girl's mother Judy Timbery said she was disgusted by the police treatment of her daughter.

"I was appalled, I couldn't believe it. Seeing how he handled my daughter, we're supposed to trust the police, and when you see something like that, who can you trust?" she said.

Then 16, Melissa had been celebrating a friend's birthday.

She was with a group of teenagers outside a McDonald's restaurant. Several of them were intoxicated, and Melissa was later charged with resisting and hindering police.

The magistrate in the case said the police officer exhibited "an inordinate amount of force".

"It frankly beggars belief," Magistrate Hogg said.

Aboriginal Legal Service solicitor Claire O'Neill defended Melissa in court.

"She was a 16-year-old girl out in the city on a summer's night in January. The magistrate described the girls she was with as being a nuisance, and that's as high as it got," she said.

Police investigation found arrests 'unnecessary' but lawful

A later internal police investigation found that the arrests of Melissa and her friend Noeleen Kane were unnecessary. The police inquiry maintains however, that the arrests were lawful.

Ms Kane, then 16, was arrested for swearing. She was later released.

Melissa Dunn's friends described the 16-year-old as a caring girl with a big heart. ( ABC News )

The police inquiry found that the girls should have been issued with court attendance notices, instead of arrested.

The police officer involved was later counselled and retrained in restraint techniques.

Ms Timbery says she will lodge a civil claim over Melissa's arrest.

Redfern Legal Service lawyer David Porter has pursued the issue through the internal police complaints process.

"The force used was not only unnecessary but the situation in which the police officer used force was created by himself failing to use his powers of arrest properly," Mr Porter said.

Three days after the court case ended, Melissa was found dead in a park in Maroubra in Sydney's south.

Her friends said she had an argument with her boyfriend.

She was known as a happy, friendly teenager.

"She was a good person," her friend Leila Zaroual, 18, said.

"She cared about a lot of people, she had a good heart. She was someone you could talk to when you needed someone."

With her friends, Melissa often drank and used drugs.

"They liked to party, drink, smoke marijuana, she did try the ice and she didn't like it," her mother said.

"I knew that she smoked dope, I didn't believe it at first, I was in denial, then I saw her and that was it, I said 'don't do it here'."

Melissa also had a history of self-harm.

"She was a cutter, she cut her arms a few times, and every weekend after weekend I was up at the hospital bringing her home," her mother said.

"We went to counselling together, that didn't help."

Aboriginal Social Justice Commissioner 'shocked' by footage

There is no evidence to suggest that the arrest and trial of Melissa contributed to her death.

But Ms Timbery is still furious at the police officer involved.

"It just made me so angry, no phone call from them or anything, not that it's gonna bring her back," she said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 14 minutes 37 seconds 14 m CCTV footage of violent arrest questions police training and exactly what happened to a young girl ( Hayden Cooper )

After viewing the CCTV footage of the arrest, Aboriginal Social Justice Commissioner Mick Gooda said he was shocked.

"I think any parent in Australia would be very worried if they had their kids treated like that, that's my first reaction, how would I feel if it was my daughter?" Commissioner Gooda said.

He says it raises serious questions about how police handle vulnerable teenagers.

"How do you deal with Aboriginal kids who might get a bit lippy and a bit mouthy?" he said.

"[It] doesn't justify that sort of treatment that we've just seen. I'll be contacting the police to have these discussions about what can we do in a training sense to make sure that this sort of stuff doesn't happen."

Officer involved in Melissa Dunn's case retrained after arrest

NSW Police have issued a statement about the case.

"NSW Police conducted an investigation into the officer's actions in 2012," the statement said.

CCTV captures NSW police dragging Melissa Dunn in a headlock. ( ABC News )

The investigation led to the officer being counselled and retrained.

The initial investigation and the subsequent reviews found no evidence of criminal misconduct in relation to the officer's actions.

"A coronial inquest into the teenager's death resulted in no adverse findings against police," the statement said.

Several times a week, Ms Timbery visits the park where Melissa died.

"I love my daughter, I miss her so much," she said.

"Sometimes I think she's still here, she's gonna walk through the front door, but I know it's not gonna happen because I dressed her, I even got her baptised before we buried her.

"It's just not fair."