Former NT police commissioner John McRoberts has been charged with attempting to pervert the course of justice in relation to a fraud investigation of a now-jailed travel agent.

In January 2015, McRoberts was asked to resign from his position as police chief over a perceived conflict of interest.

Darwin travel agent Xana Kamitsis was jailed in December 2015 for defrauding a government pensioner travel concession scheme of around $124,000.

During Kamitsis' trial, the court heard she had had an intimate relationship with McRoberts and another senior police officer.

McRoberts is due to face Darwin Magistrates court on Tuesday.

In the wake of McRoberts' resignation, three investigations were launched, by the Northern Territory ombudsman, the NT whistle blower commissioner and a separate probe by the Australia Federal Police (AFP).

In December 2015, the AFP finished its investigation, referring the matter to the NT Director of Public Prosecutions.

In June 2015, the NT ombudsman recommended a review be held into police integrity policies, including those relating to conflicts of interest, and gifts and benefits - as well as laws governing complaints against police.

The whistle blower report has yet to be made public.

McRoberts, a former assistant commissioner with the Western Australia Police, was recruited to head the NT force.

Announcing the appointment in 2009, former Labor chief minister Paul Henderson said McRoberts was "the stand out candidate among an outstanding field of applicants" for the position.

"John McRoberts has had an outstanding career in the Western Australia Police and will bring skills and experience that will be of great benefit to the Territory," Mr Henderson said at the time.

McRoberts was succeeded by Reece Kershaw, who was announced as NT Police Commissioner in April 2015.