The allegations relate to Ronald Thomas, formerly a teacher at Tasmania's elite Hutchins School, who now lives in Tangimoana, near Bulls.
Mr Thomas, aged in his late 70s, has denied allegations of historical sex offences.
Two of his former students made claims to Tasmania's Royal Commission into Institutional Responses to Child Sexual Abuse.
The commission, investigating allegations of abuse at Hutchins in the late 1960s, named Mr Thomas in November.
The commission and Mr Thomas' alleged victims believed the teacher was dead. But last month The Australian newspaper revealed Mr Thomas was living in a rural Manawatu dairy-farming community.
Today, Tasmania police said officers had returned to Australia and were now preparing a report for the director of public prosecutions.
"Tasmania police is investigating complaints against a former Hutchins teacher and will prepare a report for consideration by the DPP," a spokeswoman said.
When NZME. News Service visited Mr Thomas last month, he was home but did not come to the door.
But his partner said Mr Thomas had lived in New Zealand since about 1973 or 1974 and had taught "all over New Zealand."
He said Mr Thomas had been asked to give evidence to the commission and that he strenuously denied the claims.
"Of course he says it's not true," Mr Thomas' partner of about six years said.
The Teachers Council said Mr Thomas became a registered teacher in New Zealand in 1990, passed a criminal record check and was endorsed by his principal as part of the registration process.
The Australian said Mr Thomas disputed evidence former Tasmanian police commissioner Richard McCreadie gave to the royal commission.
Mr McCreadie told the commission Mr Thomas confessed in 1970 to molesting a boy.
"I made no statement; no confession statement," Mr Thomas told The Australian. "There was never any question of an arrest."
Mr Thomas told The Australian he stayed at the school until late 1970, leaving to take up a long-planned post in Western Samoa. The timing was purely coincidence!