A gunman remains on the run five years after shooting a Sydney father dead while he was taking the bins out in a case that continues to leave detectives stumped.

Adrian Buxton, then 31, died from gunshot wounds on May 19, 2016, after he was shot in the driveway of his property on Coral Pea Court, Colyton.

His wife and young son were home when he was brutally gunned down.

Despite extensive inquiries, and suggestions the shooting was part of a series of gang-related executions, police are yet to find his killer.

Detectives from the State Crime Command’s homicide squad established Strike Force Thistleton to investigate the father-of-one’s murder.

And on Wednesday the NSW government offered a $1m reward for information into Mr Buxton’s death.

Initial reports suggested one of the bullets hit Mr Buxton in the head before two men were seen running from the scene.

It is believed Mr Buxton was a member of the Parramatta chapter of the Nomads outlaw motorcycle club.

NSW Police combed CCTV footage that revealed three cars travelling together in the area at the time of his murder. One of the cars was later seized for forensic examination.

“In September 2016, police conducting a separate investigation seized a firearm during a search warrant at a home in Lime Street, Cabramatta. Two men were arrested and charged with firearm-related offences,” NSW Police said in a statement.

Ballistic examination later linked the weapon to Mr Buxton’s murder, but the person who pulled the trigger remains at large.

Months later Antonio Hermeiz, 20, was gunned down on December 23, 2016, at a reserve in Wetherill Park in Sydney’s southwest.

Before he was gunned down Mr Hermeiz was being investigated for links he had with the shooting murder of Mr Buxton in May.

When police arrived at the park last December, they found Mr Hermeiz dead, and another man, 18, had also been shot.

While investigating Mr Hermeiz’s death, police revealed he had possession of a black Audi Q7 that was involved in Mr Buxton’s murder.

The vehicle has not been located.

Inquiries into Mr Buxton’s death continue and police are urging the public to come forward with any information.

Police Minister David Elliott described the murder as a “brazen and organised act which had no place on the streets of Sydney”.

“I am optimistic that this reward will help detectives to obtain the evidence they need to bring someone to account for their criminal behaviour,” he said.

Mr Buxton’s family released a statement that described him as a loving son, brother, husband and father.

“He was taken from us far too soon, and we wish that he was still with us today to see his son grow,” they said.

“On behalf of our family, we want to thank the community for their support and are grateful that a reward is now on offer in the hopes that one day we may find justice for Adrian.”

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