Seven Die In Guatemalan Prison Riot
The Washington Post (From Reuters) : November 22nd 2008

Summary:
Seven inmates have been killed in a prison riot between members of MS-13 and the 18th Street Gang. The riots took place at Pavoncito prison in Guatemala, which holds almost 900 prisoners, mostly drug offenders. The riots were reportedly caused when a transfer of prisoners from another prison occurred. Apparently, as part of the killings several of the killed were decapitated and their heads were put on stakes.

Comment:
MS-13 seems to derive its culture from several prisons in El Salvador. There have been instances in the past where murders on US soil were conducted on orders originating from prisons in El Salvador. However, as this article illuminates, there are MS members in prisons in large numbers throughout Central America.

Link:
http://www.washingtonpost.com/wp-dyn/content/article/2008/11/22/AR2008112201542.html