Our county jail in 2012-2013, the deputy sheriff was part of a group trafficking across the border and selling drugs to inmates in the jail. The FBI had been investigating the trafficking and arrested the deputy sheriff as part of that bust. That is when we all learned he had been selling to our loved ones in jail.
In the state prisons, there are lots of drugs. The majority appears to be brought in by the employees, including the correction officers.
There have been a lot of news stories and investigative reports on you tube and Amazon that show drugs and cell phones being brought in by guards. Part of the problem is they are not paid well - about $14 an hour on average in AZ. A couple of times a month bring the stuff in and they have doubled their income for the month. It's illegal and morally wrong, but I don't think it will change until we provide better training and a reasonable income for the guards/corrections officers.