In 2002 Tracie-Marie Seipel, an acrobatics teacher at Sydney studio RG Dance, noticed Grant Davies, the studio director, touching students inappropriately.
Then in September 2006, Ms Seipel overheard a 14-year-old female dance student talking on the phone to a friend.
Ms Seipel heard the student calling Grant Davies a pa-dophile.
Ms Seipel asked the student why she had said that about Davies.
The student alleged that Davies had been sending inappropriate messages to two of her friends.
Ms Seipel and the students went to the police.
Davies was investigated - but not charged.
Police said parents were reluctant to have their children testify in a trial.
Parents were told at a specially convened meeting that the whole thing was a misunderstanding.
Ms Seipel and the girls who had made the allegations left the school.
In 2009, Grant Davies persuaded a mother to send him inappropriate photographs of her daughters.
The mother said when she did not respond to Davies, he "threatened to destroy me and my daughters ... expose me and what I was doing ... and release the images of me and my daughters on the internet".
She said sending videos and images reached its worst point in 2012.
"I eventually became trapped and didn't know a way out."
In 2013, the girls' father became concerned about an unusual number of messages between his wife and daughters and Davies.
He also heard about inappropriate behaviour by Davies during a dance trip to Broken Hill.
The girls told their father that Davies "wanted to see their bodies so that he could connect with them and make them stars".
The girls' father went to the police.
Davies was arrested in May 2013.
The girls' mother was also arrested and served 18 months in prison.
Her name will be put on a child s-x offender's register and she will be monitored.
In September 2015 Davies admitted 28 child s-x offences.
One female student was r-ped seven times.
Davies is expected to be sentenced in May 2016.
Tracie-Marie Seipel said she felt sick when Davies was not charged in 2006.
"It was all too easy for people to call me a liar."
"I was never a 'whistleblower', I was a 'troublemaker' and those children were never 'victims', they were just 'bratty little liars' who couldn't cope with not getting the front row," she said.
"The ramifications for those girls who came forward in 2006 - nine years of being labelled a liar, of not being believed, of having trouble finding work because they were troublemakers," she said.
"Me included, I was a troublemaker, not a whistleblower, it's had a huge impact on all of our lives."