The wall displays the names of dozens of New South Wales police officers who lost their lives on the job, and is the site of the state’s annual National Police Remembrance Day service in September.
On Friday the NSW Police Wall of Remembrance was marked with scratches and abusive messages.
About 11.15pm, officers found the wall had been desecrated further, with black graffiti on the panels and the ground in front of the memorial.
Police believe both incidents are linked.
Earlier in the evening, the 30-year-old man believed to be responsible was arrested near the pedestrian overpass at The Domain following information from the public.
Police said the man resisted arrest and smashed the rear window of a police car as he was being taken to Day Street Police Station.
He was then taken to St Vincent’s Hospital to be treated for a possible medical condition about 11:00pm.
Officers said they expected to charge the man over both incidents once the 30-year-old was released from hospital.
On Saturday, police said the panels would need to be deconstructed and be professionally cleaned.