Update
Two bodies, believed to be those of Luke Davies and Jesse Baird, have been found in surf bags on a property at Bungonia, near Goulburn.
Police said the discovery followed information provided by the police officer charged with the double murder, Senior Constable Beau Lamarre-Condon, 28.
Police interviewed Lamarre-Condon on Tuesday morning in Silverwater jail.
The property where the bodies were found is about 20 minutes drive from that searched by police yesterday.
Homicide Squad chief, Superintendent Danny Doherty, said the surf bags were found about 2pm today, partially covered by debris and with some other items.
Superintendent Doherty said, "The first phone call was to the families, to let them know".
Earlier
Police investigating the alleged murder of Luke Davies and Jesse Baird are conducting further inquiries at Grays Point and have begun a search for evidence in Royal National Park.
In a further development this afternoon, a second property in Bungonia, near Goulburn, has been declared a crime scene, and police have scheduled a news conference for 3.30pm to provide an update.
The initial police statement on Tuesday said, "Homicide Squad detectives - with assistance from specialist police resources - continue to conduct inquiries and searches as new information comes to hand under Strike Force Ashfordby".
"Today (Tuesday), canvassing will continue at Grays Point and an evidentiary search has commenced at the Royal National Park off Sir Bertram Stevens Drive, near the intersection of Bundeena Drive," the statement said.
The further media alert said senior police would "address the media in relation to ongoing investigations under Strike Force Ashfordby after investigators established a crime scene at a second property at Bungonia, this afternoon".
A van, which police say is integral to the investigation, was located at Grays Point on Friday.
Police returned to the area late yesterday and again this morning, speaking with residents and seeking CCTV recordings.
Meanwhile, it has been established Senior Constable Beau Lamarre-Condon, who has been charged with two counts of murder, is not attached to the Sutherland Shire command, as earlier reported.
A senior police source said the officer was attached to Youth Command, and worked from Miranda Police Station along with other Youth Command officers.
Police media would not comment on a report in The Sydney Morning Herald, which said Senior Constable Lamarre-Condon was working in youth liaison in the Rockdale area.
A previous police media statement said only that the charged man was "a senior constable attached to a specialist command".
The NSW Police website says "Youth Officers are the administrators of the Young Offenders Act for NSW Police".
"As part of their duties, they are responsible for delivering cautions and referring children and young people to youth justice conferences.
"The Youth Officer role also involves implementing strategies to reduce juvenile crime including: crime prevention and safety talks at schools, juvenile crime reduction programs; and networking with other agencies.
"They are the primary point of contact between NSW Police and Youth Justice NSW. There is a Youth Officer at each of the 80 Police Area Commands or Police Districts across NSW."
Deputy Police Commissioner Dave Hudson told a media conference on Monday the gun police allege was used to murder Luke Davies and Jesse Baird was "signed out from Miranda police station where it is normally stored" on Friday February 16, three days before the alleged murders, for "user-pay duties" - a protest rally held the following Sunday.
"Post the incident, we believe the gun may have been stored at Balmain police station - we believe he may have been residing with his mother - before being returned to Miranda the following day." Mr Hudson said.