The father of a man charged over a crash that killed a Sydney brother and sister has himself been charged with helping to cover up his son's alleged crime.
Johnson Kokozian, 20, was allegedly behind the wheel of a speeding high-performance car when it crashed into another car, killing the siblings, in the city's southwest on Friday night.
Alina Kauffman, 24, and her 15-year-old brother Ernesto Salazar died just 200 metres from their Heckenberg home.
Kokozian's 61-year-old father was arrested in Cartwright shortly after midday on Wednesday and was later charged with concealing a serious indictable offence and hindering the police investigation.
He was granted conditional bail and is due to appear at Liverpool Local Court on October 19.
NSW Police allege that after the crash Kokozian, his 22-year-old partner, Tiana Savignano, and his father discussed a plan to cover up the 20-year-old's involvement.
They are also accused of making false reports to police in the aftermath of the deadly collision.
Kokozian's partner and another man, Cruz Davis-Tuka, 21, were also arrested on Wednesday and hit with similar conceal and hinder charges.
Savignano allegedly called triple zero about an hour after the crash and knowingly gave a false statement.
The 22-year-old was granted bail with conditions on Wednesday despite police arguing in court she could make further attempts to interfere in the investigation.
"The fact that she allegedly misguides police, in the early critical stages of this investigation (is) not only an egregious breach of community expectation, but of law," police prosecutors told Liverpool Local Court.
Kokozian has been charged with aggravated dangerous driving occasioning death due to the alleged excessive speed.
Police allege he fled the scene after crashing a Mercedes-Benz AMG while travelling at nearly double the speed limit for the 50km/h zone.
Davis-Tuka remains in custody and is due to apply for release on Friday.