After being arrested at Singleton Police Station, a 42-year-old man appeared at Muswellbrook Local Court

A MAN appeared in Muswellbrook Local Court on Wednesday after an additional charge was laid by detectives investigating the alleged murder of Clint Starkey on the Central Coast two years ago.

Just after midnight on Thursday, April 6, 2017, Mr Starkey, aged 42, presented at Gosford Hospital with serious head injuries.

He was later flown to Royal North Shore Hospital, where he remained in a critical condition until he died on Monday, June 12, 2017.

Detectives from the State Crime Command's Homicide Squad, assisted by Brisbane Water Police District, established Strike Force Bartondale to investigate the assault and circumstances surrounding Mr Starkey's death.

Their inquiries revealed he was assaulted at a service station at Peats Ridge, which was examined by specialist forensic officers.

Strike force investigators have charged nine men - including six with murder - as part of their investigations so far.

They remain before the courts.

Of those, a 41-year-old man was arrested at a Mangrove Mountain home on Thursday, April 6, 2017, and charged with a number of offences, including conceal serious indictable offence of another person and firearm offences.

Following further investigations, the now 42-year-old man was arrested at Singleton Police Station on Tuesday, June 11.

He was charged with murder and refused bail to appear at Muswellbrook Local Court on Wednesday, June 12.

Investigations under Strike Force Bartondale continue.