And even if the zip was broken she would not be the first person to be caught because of stupidity even though some precautions were taken to hide their crime. In IMO cops are not that smart as a rule and most crims are either caught because they did something stupid while commiting the crime, were dobbed in, or had a big mouth.
FAct remains finger prints would not have proven her innocence it would have proven her guilt but there was still a strong case against her without this evidence.
Her defence was based around someone planting the drugs but the only evidence to support this was specualtion and here say. This evidence was not considered convincing and would not have even been allowed in an AUstralian court.
Reality is if this was a case in an Australian court the verdict probably would not have been any different