Five other people were in a Cronulla unit when a man fell to his death from a fifth floor balcony.
The five people included a man, 40, who was the subject of an apprehended violence order (AVO) and the woman named in the order, with whom he should not have had contact.
Police later charged the man, 40, with breaching an AVO.
A police strike force has been set up to investigate the death of the man, 64, who was fatally injured when he fell from the unit complex in Deeban Walk just after 10pm on Thursday.
Acting commander of Sutherland Police Area Command, Acting Superintendent Steve Patton, said it was difficult to establish what had transpired.
Mr Patton said police who went to investigate were alerted by passers-by to a man acting suspiciously nearby.
"He was subsequently charged with contravening an AVO, which was unrelated to the deceased," Mr Patton said.
"That man, along with four other people in the unit at the time, are assisting police with inquiries.
"We are asking for anyone who was on Deeban Walk or in the vicinity of Tonkin Oval at the time to come forward if they saw anything that can assist our inquiries.
"Strike Force Chore has been set up by Sutherland detectives to continue investigations."
The man charged with contravening the AVO was refused bail to appear at Central Local Court today (Friday).
A man, 64, has died after falling from a home unit balcony in Cronulla overnight.
Just after 10pm on Thursday, emergency services were called to a unit complex on Deeban Walk following reports a man had fallen from a fifth floor balcony.
"Officers from Sutherland Shire Police Area Command and NSW Ambulance paramedics attended and found the body of a 64-year-old man on the ground below," a police statement said.
"A crime scene was established as investigations into the circumstances surrounding the death continue."