Judge Jane Farish remanded Boyd in custody to be sentenced on August 10.
The Crown said that Boyd assaulted the girl on two occasions.
Both times the girl pleaded with Boyd to stop, the Crown claimed.
Afterwards, Boyd allegedly told the girl not to tell anybody what had happened.
The girl's school later heard of the allegations and police were informed.
On August 7, 2011, Boyd was arrested.
He appeared in court and was granted electronically-monitored bail, with conditions that he stayed at a home address at all times, except for approved absences, and to his surrender passport and not to apply for a new passport.
He was allowed to go shopping every Thursday with an approved support person.
In January 2013, he applied for an extension to his approved release so he could attend a doctor's appointment.
It was approved on the condition that Boyd, who got married in August 2012 and took his wife's surname, return to his house by 7pm on January 24.
However, he fled to Christchurch where he used a passport that he obtained under his adopted wife's surname to board a flight to Sydney -- four days before his trial.
Boyd was arrested by Australian Federal Police in May 2013 and extradited to New Zealand in January last year.
The Crown said that Boyd's attempts to flee were an "important piece of evidence".
The defence case was simply that none of the offending happened.
Boyd had applied to have his first trial transferred from the West Coast to Christchurch.
Defence counsel Marcus Zintl said the coast is a small community where there is rumour and gossip and Mr Boyd didn't believe he would get a fair trial there.
Boyd said he used his wife's surname for "cultural reasons" and that he'd bought a return ticket which he'd intended to use.
But Crown prosecutor Anselm Williams said Boyd's account was "inconsistent".
The real reason he fled, Mr Williams said, was because he was afraid the victim would tell the truth and he was "unable to take responsibility for that".
He said the victim had relayed a detailed, consistent and clear account of the attacks.