Prosecutor and investigators say Reta and Cardona were recruited into a group called "Los Zetas, " a group made up of former members of the Mexican special military forces.
The cases against Cardona and Reta -- both are in prison serving long prison sentences for murder -- shed new light into the workings of the drug cartels.
Reta's face became covered in tattoo markings. (Prosecutors say during his trial Reta used make-up to cover the facial markings.) And both sported tattoos of "Santa Muerte, " the Grim Reaper-like pseudo-saint worshipped by drug traffickers.