John Setka's estranged wife is accused of telling a private investigator she wanted the union heavyweight killed and inciting someone to conspire to commit murder.
Emma Walters, 46, faced Melbourne Magistrates Court by video link on Wednesday after being charged last week over an alleged plan to murder the Construction, Forestry, Mining and Energy Union boss.
She has been charged with making a threat to kill Setka to private investigator Adrian Peeters on March 21, intending that Mr Peeters would "fear such threat would be carried out" or "being reckless as to whether or not" he would fear the threat would be carried out, court documents stated.
Walters is also charged with inciting someone to acquire a firearm without a permit, and inciting a person to commit conspiracy to murder.
Police investigators searched her Footscray home last week and seized a mobile phone.
Prosecutor Laura Zubreckyj told the court on Wednesday that body-worn camera footage would form part of the evidence.
She asked the magistrate to attach new conditions to Walters' bail about who she can contact, banning her from speaking to Mr Peeters or any past and present employees of his Group One Investigations firm.
Walters has denied all allegations. Her bail was extended and she will next face court on July 17.
Setka and Walters have been involved in a long-running legal battle involving allegations he committed acts of domestic violence, which he has denied.
She is also suing the Victorian government over claims police failed to protect her.
At the same time Walters was in court, Setka was speaking at a CFMEU rally in Melbourne's CBD, as part of the union's national day of action on industrial relations reform and the abolishment of the Fair Work Ombudsman.
