Crown prosecutor Deborah Davies asked the judge to sentence Marshall to preventive detention.
Preventive detention means an offender will be held for life unless they prove they are not a risk to the community.
Marshall’s offending was lengthy and premeditated, while he denied almost everything when interviewed by psychologists.
“He has caused lengthy, serious harm to this community and this young girl,” Davies said.
The judge said those factors played a part in the sentence, but preventive detention could not be justified.
While there was a need to deter and denounce Marshall’s crimes, and he had been assessed as high risk of reoffending, he had never had the chance to undertake treatment for his sexual deviancy.
His criminal history had no sexual offending, and he would likely be subject to an extended supervision order when released, a judge said.