This morning an ACT Supreme Court jury Michael Alan Gillard, 57, guilty of eight sexual offences against the then-teenage girl between 1995 and 2000.

But the jury cleared the man of another four indecency charges.

He was accused of committing some of the offences when the victim and her sister stayed with him in Canberra during school holidays.

The jury found Gillard forced the girl to perform oral sex on him in the presence of her younger sister.

He was also found guilty of possessing child pornography after taking nude photos of the girl with her legs spread.

Gillard's defence had argued any sexual activity between the pair only took place after the victim turned 16 and she consented to the acts.

But the Crown had argued that even if the victim appeared to submit to the sex acts, Gillard had abused his position of authority.

The jury deliberated for just under a day before returning to court at 11.15am with their verdict.

Chief Justice Terence Higgins thanked the jury for their efforts in the face of a complex case with numerous charges.

Gillard's bail was continued and he will be sentenced in December.