"The history of supergrass trials is that the overwhelming majority, if not all of them, have always put in the witness box people of poor credibility, " he said.
Brian Ervine, the new leader of the political party associated with the UVF, told Spotlight that a senior north Belfast loyalist's apparent decision to become a "supergrass" could harden the position.
Mr Rees was one of five men accused of murdering Mr Morgan in 2008, but after almost two years of legal wrangling, the trial collapsed in March 2010 when "supergrass" evidence was deemed to be unreliable.