I don't want to comment. Take my word for it and read through the following links:
* Yemen's Jews. The End
Background, 2007: Yemen's few Jews face rebel threats
* Analysis: How many Jewish terrorists are still out there? - A Jewish person from USA, father of 4, goes berserk - plots and carries out violence against Arabs and lefties.
* Does Israel check olim's criminal past? - An immigrant from Russia butchers a family with their children