Fabian Meharry, 28, who is well known in the Echuca BMX scene, has pleaded guilty to 62 child sexual crimes against 22 young victims.

This includes persistent sexual abuse of a child under 16, producing, publishing and possessing child pornography, grooming children using a carriage service, and sexual penetration of a child under 16.

He was initially charged with more than 100 child sexual crimes, but it is understood many have since been wound up into charges representative of his conduct between December, 2006, and August, 2015.

Meharry, a registered sex offender, appeared in the County Court in Melbourne for a pre-sentence hearing on Monday.

The court heard he mainly used female aliases to befriend victims online, many of whom told him their age.

Prosecutor Brendan Kissane, QC, said Meharry asked the girls to send him sexual photos of themselves.

When they refused to perform sexual acts according to his instructions via webcam or Skype, he would threaten to publish the photos online and to take his own life. 

One of the victims was given 30 seconds to comply with his demands, before he threatened to send photos of her to her mother, the court heard.

When she said she would call the police, he told her she would also get in trouble because she had committed a crime herself by sending him sexual photos.

A victim cried as she read her victim impact statement to the court, and addressed Meharry directly: "I should have been given choice to grow and blossom on my own accord."

The victim, who has been diagnosed with post-traumatic stress disorder, said she still felt responsible for the abuse.

Meharry made her feel ashamed and used her weaknesses against her to ensure she did not tell anyone. "You have made me more broken than I ever was before," she said.

Judge Elizabeth Gaynor told her that the abuse was not her fault and acknowledged the difficult task of reading her statement in court: "Go away and remember that's what you did today. Hopefully that will help you in the years to come."

The pre-sentence hearing continues.