ACT Policing officers had a search warrant and were accompanied by WorkSafe ACT inspectors when they went to premises outside Gosford on the central coast where the piece of machinery that killed builder Ben Catanzariti, 21, had recently been serviced.

The Canberra Times has obtained the routine maintenance report on the concrete pump compiled just weeks before Mr Catanzariti's death on a Kingston Foreshore building site on July 21.

The young worker, originally from Griffith in NSW, was killed instantly when he was hit with the boom of the concrete pump while working on an upmarket apartment development in the lakeside precinct.

The maintenance report reveals that several vital repairs were required to the pump.

The Canberra Times understands that those repairs were carried out before the accident and that the investigation is centred on how the work was done.

Investigators are also looking at whether the correct exclusion zone was enforced around the equipment while it was being used on July 21.

Both police and the WorkSafe Commission remain tight-lipped about their inquiries. ACT Policing confirmed only that it executed the search warrant on the premises in the Gosford area in late July, days after Mr Catanzariti's death.

Work Safety Commissioner Mark McCabe simply said his inquiries were continuing and warned that they might take some time.

''I understand the desire of friends and relatives of the deceased for there to be prompt action in respect to any breaches in the law that may have led to this accident,'' Mr McCabe said.

But he said: ''It is equally important that if there is to be a case for a prosecution, that the case be well prepared and not flounder because it has been prepared hastily.

''It is not uncommon for such a case to involve complex technical evidence and for it to be vigorously defended.''

But Mr McCabe said that two other investigations into Canberra workplace deaths, those of Wayne Vickery, killed by a grader on a West Macgregor building site in December 2011, and truck driver Michael Booth, electrocuted in March at a site in Turner, were ''well advanced''.

Mr McCabe and former public service commissioner Lynelle Briggs are due to hand the report of their inquiry into workplace safety in Canberra to Workplace Safety Minister Simon Corbell.

Master Builders Association executive director John Miller urged the minister to increase funding to Mr McCabe's office.

''MBA-ACT has reinforced in its submission to the Briggs inquiry the need to ensure a properly resourced and effective WorkSafe ACT,'' Mr Miller said on Thursday.

''We believe that WorkSafe ACT Commissioner Mark McCabe has done an excellent job but is woefully under-resourced.

''It is totally appropriate that the oversighting and regulation of site safety falls to an independent body.''