Fourth man charged in kidnapping and murder of grandpa

The man will face Mt Druitt Local Court on Wednesday.

Three others have already been charged and remain before the courts.

NSW Police Commissioner Mal Lanyon said the young man arrested on Tuesday was involved in the initial abduction of Mr Baghsarian.

"We're alleging this 19-year-old actually provided a firearm that was used in his initial kidnapping," Mr Lanyon told 2GB radio.

Investigators are continuing to look into other possible suspects, he said.

Mr Baghsarian's violent kidnapping shocked Australia after police revealed the widower was not the intended target and had been taken in a case of mistaken identity.

Police made several public appeals, urging the kidnappers to release the 85-year-old and return him to his family.

But on February 24, his body was found near a golf club in Pitt Town in Sydney's northwest.

Police suspect the perpetrators aimed to abduct a relative of Sydney businessman Dimitri Stepanyan, who lived on the same street as Mr Baghsarian, with the hope of receiving a $50 million ransom.

Investigators believe Mr Baghsarian was killed on the night of February 14 at a makeshift stronghold in Dural, about a half-hour drive from where his remains were found.

The ordeal is part of a growing number of underworld attacks that have permeated Sydney streets, with Mr Lanyon saying the city is dealing with a very different organised crime environment.

"We are seeing young people predominantly being contracted online to conduct very serious criminal activity," he said.

"There are a lot of young people who are seeing what they believe to be an easy dollar but not understanding the ramifications ... the crime of murder carries life."

Mr Baghsarian's family described the harrowing ordeal as a nightmare, remembering him as a devoted father, brother, uncle and grandfather "who would never hurt a fly".