Coleen Lamarre, 63, was arrested at Balmain in Sydney's inner west on Wednesday morning and charged with perverting the course of justice.
She has previously attended court as her son's legal proceedings continued, but largely stayed silent as she watched on.
The 63-year-old is set to appear in a bail court on Thursday.
Her son is accused of fatally shooting TV presenter Jesse Baird and his flight attendant partner Luke Davies at their inner-city Sydney home with his service pistol in February 2024.
Police allege the former officer later bundled their bodies into surfboard bags and dumped them at a rural property in Bungonia near Goulburn.
They were found eight days later.
The 30-year-old, who briefly dated Mr Baird, has pleaded not guilty to their murders.
Lamarre-Condon joined the force in 2019 and was the first serving NSW police officer charged with murder in several decades.
The then-senior constable later handed himself in, charged and eventually sacked by NSW Police.
He faces two counts of domestic violence-related murder and aggravated break and enter.
His case will return to court on May 29.
The proceedings have become one of the state's most high-profile criminal cases in recent years.
In a previous hearing, Lamarre-Condon said he opposed any orders for a closed court at his trial, saying he "will not be silenced".
The prosecution has hinted at calling hundreds of witnesses to his trial.
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