Underworld figure George Marrogi is reportedly being investigated over a plot to kill an associate from behind bars.

The Herald Sun reports the investigation stems from phone taps that also led to Marrogi being charged with running a major drug smuggling operation from his prison cell.

John Silvester from The Age told 3AW Breakfast that Marrogi would soon face sentencing over a 2016, following a number of aborted trials.

He said it was a “really interesting” case.

Press PLAY below to hear his insights