A defence force whistleblower who was a key SAS source in stories about Victoria Cross recipient Ben Roberts-Smith has outed himself in court this week saying he needed to be a “voice from within”.

The soldier, known as Person 7 for national security reasons, revealed it was him who had provided key information to journalists Nick McKenzie and Chris Masters during Roberts-Smith’s defamation trial against The Sydney Morning Herald and The Age.

Across more than 10 weeks, the court has heard damning allegations that Roberts-Smith executed prisoners or instructed subordinates to execute them as well as detailed evidence about operations in Afghanistan Australian SAS soldiers were involved in.

Roberts-Smith denies all allegations that were published by The Herald and The Age.

Today on Please Explain, investigative journalist Nick McKenzie joins Nathanael Cooper to discuss Person 7 and the Ben Roberts-Smith case.