He was first investigated in 2002 when he was responsible for the Innisfail police district.
Sources have told The Courier-Mail that police officers and civilians lodged complaints against him over his style of management.
The Queensland Police Service refused to reveal the outcome of the investigation. Insp Swan was transferred to Cairns, where he was made responsible for upholding professional practices of police.
The position involved handling complaints against police and administering disciplinary measures.
He was again investigated by the Ethical Standards Command and then Assistant Commissioner Peter Barron for allegedly leaving an offensive phone message for a Cairns Post reporter in March 2005.
After a two-week investigation, the QPS said "appropriate action" had been taken but declined to divulge details.
Later that year, he became the northern stations inspector, overseeing about a dozen police stations north of Cairns. The QPS confirmed officers attached to Cooktown police station had lodged grievances against him including alleged use of offensive language to describe indigenous people and alleged threatening treatment over staffing matters.
Police also told The Courier-Mail Insp Swan was accused of urinating on the front lawn of the Cooktown Court House on November 20, 2008.
Despite lodging the grievances last year, officers have only recently been interviewed and Insp Swan's responsibilities have remained unchanged.
A Queensland Police Service spokesman said no further information could be released about the investigation. The spokesman said harassment in the workplace was taken seriously by the QPS and the matter would be thoroughly investigated.
Insp Swan expressed surprise about the complaints made against him when contacted by The Courier-Mail but declined to comment on the matter.