Arson Unit detectives have charged a 29-year-old man following a 10-year investigation into a fire that destroyed the Liverpool Council Chambers.
The blaze caused more than $27 million damage.
Police have released a COMFIT image of another man, as inquiries continue.
Local police and emergency services were called to a property on Hoxton Park Road, Liverpool, about 12.35am on Sunday, August 15, 2010, and arrived to find the building engulfed in flames.
Fire and Rescue NSW deployed more than 80 firefighters and 20 units to bring the blaze under control.
No one was injured during the incident.
A crime scene was established and examined by fire investigators and specialist forensic officers.
Initial inquiries revealed the building's alarm had been activated just after midnight, and the fire was deemed to be suspicious.
Strike Force Gideon was established by detectives from the Financial Crimes Squad's Arson Unit to investigate the circumstances surrounding the fire, which caused more than $27 million damage.
Following extensive investigations and several public appeals for information, Strike Force Gideon investigators arrested a 29-year-old man at George Street, Liverpool, just after 4pm yesterday Wednesday, June 17 2020.
The man was taken to Liverpool Police Station and charged with destroying property in company use fire (greater than $5000) and aggravated break and enter commit a serious indictable offence.
Police will allege in court that the man was involved in lighting the fire, after breaking into the Liverpool Council Chambers, while in the company of others.
He was refused bail and is due to appear at Liverpool Local Court today Thursday, June 18 2020.
Arson Unit Commander, Detective Chief Inspector Richard Puffett, said yesterday's arrest is a direct result of the dedication detectives have applied to a decade-long multimillion-dollar investigation.
"Strike Force Gideon detectives have followed numerous lines of inquiry which culminated in the arrest of a man at Liverpool yesterday," Det Ch Insp Puffett said.
"For ten years, the Arson Unit has diligently reviewed new information about a possible motive for the fire and new enhanced examination techniques ultimately led to a breakthrough in the investigation.
"Not only did this fire cause extensive damage and disrupted Local Government - it put the lives of neighbouring residents and emergency service workers in danger," Det Ch Insp Puffett said.
As investigations continue, detectives have released a COMFIT image of another man seen in the area at the time of the fire and who may be able to assist with inquiries.
The man depicted in the COMFIT image is described as being of Mediterranean appearance, aged in his early 20's and wearing a dark-coloured hooded-jumper.
"Anyone who may recognise the man depicted in the COMFIT image, or who has information about this case, is urged to come forward," Det Ch Insp Puffett said.
"Even though it has been 10 years since the fire, we'd like to hear from anyone whose memory may be refreshed by this image - no matter how insignificant the information may seem, it could be valuable to the investigation.
"Strike Force Gideon detectives wish to thank those in the community who have already come forward and provided details to police throughout the course of the investigation," Det Ch Insp Puffett said.
Investigations by the Arson Unit are continuing.
Anyone with information that may assist Strike Force Gideon investigators is urged to contact Crime Stoppers: 1800 333 000 or https://nsw.crimestoppers.com.au. Information is treated in strict confidence. The public is reminded not to report crime via NSW Police social media pages.