Health and Safety at Work inspectors say their investigation into the death of a construction worker in Kirk Michael could take up to six months.
Fifty-five year old Gareth Sowden from Douglas was killed when part of a structure being installed at sewage treatment works on Balleira Road, fell on him.
The accident happened on Wednesday morning - emergency services were called but Mr Sowdon died on-site.
Painstaking inquiries are being carried out to establish whether what caused the tragedy and the site will remain closed while safety procedures on the site are reviewed.
Bernard Warden from the Health and Safety Inspectorate is heading the inquiry: