Their deaths shocked the world after it was revealed Beau Lamarre-Condon, a 28-year-old police officer, was allegedly responsible.

Police allege Lamarre-Condon killed Mr Davies and Mr Baird on February 19 at around 9.50am at Mr Baird's home in Paddington in Sydney's eastern suburbs with his police pistol.

The pair's bodies were allegedly discovered in two surfboard bags covered in debris at a property in the Southern Tablelands on February 27.

Former NSW detective Duncan McNab described the slayings as the alleged "murder of the Insta age" because all three men -Lamarre-Condon, and Mr Davies and Mr Baird - had high profiles on social media.

"There was a lot of information on social media about them that the public could access for themselves," he said.

Another factor was Lamarre-Condon's past as a well-known celebrity blogger.

"He had a very bizarre backstory," he said.

Mr McNab said the final photograph of Mr Baird and Mr Davies - happily posing at a Pink concert the day before - really etched the story in the public's mind.

"The reason we are all drawn to it is because we can't get those images of two young men out of our minds," he said.

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The NSW Police constable had been in the news a number of times in the past decade.

He first made headlines in 2014 when the then 19-year-old threw a note to popstar Lady Gaga during a Sydney Born This Way concert.

Lady Gaga picked the note off the stage and read it to the crowd, creating a viral moment on social media.

The note read "two years ago I also met you at this arena for the Born This Way Ball where my life changed forever".

"I had told you something I never had the courage to tell anyone before".

"I told you that I didn't know how to come out to my family about my sexuality and I was scared to. You told me something I will never forget. 'If your parents love you as much as I believe they do, they will accept you for who you are'."

The alarm was first raised on Wednesday, February 21 after a worker allegedly discovered unusual items including bloodied clothing in a skip bin near a club in Sydney's south.

Police said a "significant" amount of blood was found at Mr Baird's Paddington home later that day.

Lamarre-Condon became a suspect and presented himself to a Bondi police station two days later. Police said he would later lead investigators to their bodies.

Police are expected to allege Lamarre-Condon only planned to kill Mr Baird, who he had briefly dated.

Mr Davies was only murdered for being in the house at the same time, according to police.

Police will also allege Lamarre-Condon engaged in stalking in the lead-up to the deaths.

Lamarre-Condon is currently detained at Silverwater prison and is next due to face court on April 23.