Girl, 16, charged with man's murder in Sydney

A 16-year-old girl has been charged with the murder of a man allegedly beaten to death in a Sydney home.

The girl is due to face a children's court on Friday after she was arrested in Muswellbrook on Thursday afternoon.

NSW Police allege she was involved in the fatal assault of a 32-year-old man found unresponsive in a bedroom of a home in Tregear, near Blacktown, in June.

The murder charge comes after the girl and two males, aged 18 and 19, went before the courts on assault charges related to the incident.

The 19-year-old's assault charge has since been upgraded to murder.

Investigations under Strike Force Armine are ongoing.