New Zealand police says Alan Langdon contravened a Family Court order by sailing his six-year-old daughter to Australia.
Mr Langdon and Que were the subject of a massive search last month, after sailing from Kawhia harbour on December 17.
It was called off after police determined they were deliberately heading for Australia on the 6.4m catamaran.
The pair reached dry land in NSW earlier this week, with Mr Langdon saying a rudder broke early in the near four-week voyage.
It had been understood Mr Langdon was in a custody dispute with Que's mother - who was in Switzerland at the time of their departure - and now police say Que should not have been taken out of the country.
"New Zealand Police are carefully considering the circumstances and information relating to the arrival of Alan Langdon and his daughter in New South Wales, Australia yesterday," Detective Sergeant Bill Crowe told 1 NEWS.
"Police will continue to liaise with partner agencies and the relevant Australian authorities as part of their ongoing investigation.
"Police have determined that Mr Langdon's actions, of taking his daughter out of New Zealand, contravened a family court order."
Police have determined that Mr Langdon's actions contravened a family court order"
Mr Langdon and Que have spoken with media since arriving in Ulladulla - south of Sydney - and were asked to sail to Port Kembia Harbour for quarantine.