TRACES of the primary chemical in marijuana have allegedly been found on Gerard Baden-Clay's father during four recent prison visits.
News Corp reported that Wolston prison workers believed Nigel Baden-Clay was receiving preferential treatment because his contact visits were not restricted after the results.
An unnamed worker claimed contact visits were usually suspended if a visitor returned three positive tests.
However Mr Baden-Clay and his family have denied any suggestions that they were linked to illegal drugs.
Mr Baden-Clay's lawyer Peter Shields said "there was no real evidence" or public interest to justify running a story about the drug tests.
"Nigel Baden-Clay and his family do not use illegal drugs," he said.