Venezuela has had terrible prisons since colonial times, as you will find out if you even read the comments of such people as Alexander von Humboldt. We already had several massacres in the times preceding Chávez.
Still, Venezuela has reached levels of decay unseen for probably a century.
Chávez came to power in February 1999. The national murder rate back then was about 19 murders per 100 thousand inhabitants. By 2003, the murder rate was twice as high (now it's almost 70 murders x 100 000 inhabitants). The state security forces, more corrupt than ever, lost control of the inner part of prisons around 2003. Since then most prisons are internally under control of gangsters. The Guardia Nacional only keeps an eye on the access, if at all as in reality they can be influenced in more ways than you think from inside.
The latest massacre in Sabaneta prison a few days back led to a new transfer of prisoners to other jails. Every time a massacre happens, a new reshuffling takes place. A Venezuelan newspaper that still (still) is critical of the government, Notitarde, managed to describe a little bit the details of the new transfer and those details can give foreigners a little glimpse into what it all is really like.
It turns out that there were 300 children living with their jailed parents in Sabaneta. 200 of them were under 9 years old and they were living at least 5 months there without going to any school.
Sabaneta had a capacity for 700 persons but there were nearly 3700.
In Venezuelan prisons if you have the money or the clout you can have not just a TV and a washing machine, but you can have your mobile phones and most importantly, a gun or two or more. Your wife or girlfriend can live with you as well.
If you don't have the money or the clout you can get killed very easily. Over 500 prisoners were murdered there last year. And Iris Varela, the woman Chávez appointed as "Minister for the Popular Power of the Penitentiary System", says everything is the fault of the previous governments.