Operation Pike, an AFP-led task force into the fire at Old Parliament House on 30 December last year, is seeking Museum of Australian Democracy guests or anyone who might have been in the area and witnessed the incident.
Three people have been arrested in relation to the fire. One person was charged with three counts of assaulting a frontline service provider, another was charged with assaulting a frontline service provider and the third was charged with hindering a Territory official.
Police said there had been ongoing protests at Old Parliament House in the fortnight leading up to the 30 December fire and a separate fire in that period.
Investigators are hopeful that people with valuable information were evacuated from the museum or were nearby at the time but who have not yet spoken with police.
Anyone who may have information that could aid investigators is urged to contact Crime Stoppers ACT on 1800 333 000, or via the Crime Stoppers ACT website, and quote reference 6993036.