74 , who previously owned and ran johnstone river crocodile farm and zoo in far-north queensland first came across the 5.2 metre croc in 1989 .
for 20 years the farmer would sit on the enormous creature 's back while he chatted to him , and never once felt as though he was in danger .
rangers had already been trying to capture gregory , who had apparently been killing cattle in eubenangee swamp near mirriwinni , 70 kilometres south of cairns for years .