The former psychiatrist of Sandy Hook massacre gunman Adam Lanza is being investigated by the Waikato District Health Board.
Dr Paul Fox's appointment to work in Hamilton is now under review, chief executive Craig Climo yesterday told the Waikato Times.
Dr Fox gave up his medical licence in the United States amid allegations he had a sexual relationship with a patient for more than a year while working in Connecticut.
He was charged with professional misconduct over the incident and voluntarily surrendered his licence to before a disciplinary hearing.
Mr Climo said Dr Fox did tell the health board before he was appointed that he had given up his licence, but the review would determine whether he disclosed all relevant information.
"We have started a review and will complete it as soon as key people involved in his registration and employment return from leave," Mr Climo said.
"As part of our review, we will look into whether there was full disclosure."
Mr Climo could not confirm the exact date Dr Fox was employed by the health board, but said he initially worked as a locum psychiatrist before becoming permanent.
He is working for the Mental Health and Addictions service in Hamilton.
The Waikato Times asked Dr Fox for comment via the health board, but he is on leave until mid-January.
A former patient of Dr Fox claimed the pair had a "personal consensual sexual relationship" for more than a year, according to a draft investigative report by the Connecticut Department of Public Health in July 2012.
She told investigators that they had sex in his office and spent time together on his boat.
Dr Fox treated school shooter Adam Lanza years before the Sandy Hook Elementary School massacre in Connecticut in which he shot dead 26 people, including 20 students in December 2012.
It remains one of the worst massacres in US history.
Dr Fox told police investigating the shooting that he last saw Lanza when he was about 15 years old, the Associated Press reported.
Lanza was aged 20 when he killed 20 pupils and six adults at the Newtown school in December 2012.
He first shot his mother to death at their home before going to the school, where he killed himself as police arrived.
Medical Council chairman John Adams said Dr Fox had provisional registration in New Zealand and was working under supervision.
He said all information included in Dr Fox's application for registration would be checked.
"If Dr Fox has withheld information, the council will treat it with the upmost seriousness," he says.