As he posed as a 15-year-old boy named "Josh," to the unsuspecting young girl Russell was a run-of-the-mill teenage boy, tackling high school and extracurricular activities.

He even sent a photo of a topless young male to complete the online identity.

But while they may have once talked of school and sport, the conversation would quickly turn, with Russell soon describing himself as having "teenage-guy-horniness" and later asking the girl to read a survey entitled "13 and 14-year-old girl's masturbation survey".

Earlier this year Russell pleaded guilty to using a carriage service to transmit indecent material to a person under 16 years of age and possessing child abuse material. The offences carry maximum penalties of seven and 10 years' imprisonment, respectively.

Dressed in a suit and carrying a copy of the 1968 science fiction novel 2001: A Space Odyssey, Russell appeared at the Downing Centre for sentencing on Thursday.

However the matter was adjourned to May next year, as a final psychiatric assessment report was received by Russell's defence barrister just one day before his sentencing.

His defence barrister requested a requalification of Russell's psychiatric assessment and that additional material be supplied by the crown before sentencing proceed.

Russell's correspondence with the girl, identified in the agreed statement of facts as EF, began in mid-June 2015 by text message, before the two exchanged email addresses.

With Russell purporting to be 15 years old, EF said that she was younger than him, but that they were close in age.

From the end of June to the start of September, EF received 667 text messages from Russell, and once they transferred communication to email he repeatedly requested photos, asked of her sexual experience and made continuous attempts to discuss oral sex and masturbation.

"It will actually help us get to know each other, if you know what I mean," he wrote.

Around July 10 Russell sent EF a survey titled "13 and 14-year-old girl's masturbation survey", stating, "all I want is for you to read everything I sent. ESPECIALLY the survey. I put in the effort to find it, you can put in the effort to read it."

According to court documents, EF told Russell that she was not comfortable with the content of his emails on multiple occasions, however he merely responded by encouraging the girl to "step out of her comfort zone", and "be ok with a little bit of uncomfortable [sic]".

Five days after she received the survey, the 13-year-old ended communication, however Russell continued to contact her on a further seven occasions, including sending her an 81-page extract of a Reddit "Ask Woman" thread entitled, "How old were you when you had your first orgasm?".

On August 20 the Australian Federal Police Child Protection Operations Assessment Centre received an online report from a member of the public.

The report had been filed by a mother who stated that her 13-year-old daughter had received sexually explicit emails containing pornography from an email account later connected to Russell.

By November 13 a search warrant was executed at Russell's home in Randwick and a number of electronic devices were seized.

On two devices AFP members found a combined total of 3195 videos and 3564 images identified as child pornography, depicting children from infancy to about 15 years of age.

A significant portion of the material was on a hard drive in a folder entitled "naughties".

In court on Thursday Judge Hoy was unreserved in his frustration that Russell's sentencing would be pushed out to May next year.

"I think it is a disgrace, the delay to this matter," he said, adding that it was "very tardy ... the way it has been dealt with".

Russell, who is on bail, will be sentenced on May 18 next year.

In the first five months of this year the AFP's child protection centre received more than 4500 reports of child exploitation, a figure greater than the number of reports received in the 2013 and 2014 calendar years.

In 2016 it received more than 8000 reports of child exploitation.