A third teenager has been charged over the alleged contract killing of a young Sydney man in what police believe was likely a case of mistaken identity.

Luke Manassa was allegedly ambushed by two men dressed in dark clothing and disguises in the driveway of a home on Driftway Drive in Pemulwuy, at 10.45pm on June 26.

The 21-year-old had just arrived at the home with his girlfriend, according to police.

A man who died in a stabbing outside a home in Sydney's west in June has been identified as 21-year-old Luke Manassa.A man who died in a stabbing outside a home in Sydney’s west in June has been identified as 21-year-old Luke Manassa. (Nine)

Manassa managed to get back into his car and drive a short distance.

Paramedics treated him but he could not be revived and he died at the scene.

Yesterday police searched a home at Blacktown yesterday and arrested a 17-year-old man.

He was charged with manslaughter, knowingly/recklessly directing a criminal group to assist with a crime and failing to comply with a digital evidence access order direction.

Police will allege in court the teenager allegedly issued the contract to carry out the attack on another man but Manassa was targeted in a case of mistaken identity.