NT top cop 'protected himself': trial

Former Northern Territory police chief John McRoberts was motivated by self-interest as he tried to derail a criminal investigation into widespread defrauding of the government that involved his then travel agent lover, a court has heard.

The month-long trial of Mr McRoberts, 59, who has pleaded not guilty to attempting to pervert the course of justice, is close to finishing with the prosecution and defence lawyers due to make closing arguments on Thursday.

Mr McRoberts' former lover, the married Xana Kamitsis who was later jailed, had been defrauding a government travel concession scheme along with numerous other Darwin travel agents.

After discovering that, Mr McRoberts "went off on a frolic on his own" and had a coffee meeting with the then-head of the NT Health Department, Len Notaras, and tried to talk him out of a criminal investigation, prosecutor Michael McHugh said when beginning his closing address on Wednesday.

Mr McRoberts' arguments to Dr Notaras and fellow police - that a prosecution of the travel agents would have damaged the NT's reputation and tourism industry, and more evidence was needed before he would let them raid Kamitsis's business - were debatable, Mr McHugh said.

"The plan to start this move way from a criminal investigation was to protect, the Crown says, himself and Ms Kamitsis," he said.

"The accused did what he did for an improper purpose ...it was all a smokescreen.

"The accused lied about the extent of his relationship. He ought to have disclosed the full extent and knew he ought not to have anything to do with the investigation."