Sydney execution remains a mystery

Three years after a 25-year-old man was shot dead at a baseball field in Sydney's southwest, an inquest has failed to shed light on who killed him.

Deputy State Coroner Theresa O'Sullivan on Wednesday referred the death of Cabramatta man To Minh Tu to NSW's unsolved homicide squad.

Ms O'Sullivan found Mr Tu died from multiple gunshot wounds in the early hours of February 21, 2013.

The one-day inquest heard he had been the subject of police intelligence reports on gang activity, drug supply and firearms.

Police also found evidence suggesting Mr Tu was planning to commit a crime the night he died.

He had a lengthy rap sheet including rape and car theft, the inquest heard.

His body was discovered at a Fairfield baseball field with four gunshot wounds including to the head from close range.

Counsel assisting, Rama Vat, said witnesses heard shots about 12.30am and saw three men standing close to the scene just before the murder.

"CCTV footage showed a red vehicle leaving the park around 1.40am," he said.

Mr Tu's former partner Vy Tran cried as the findings were read out.

"I am sorry this has been a distressing experience for you," Ms O'Sullivan told the victim's family at Glebe Coroner's Court.