@Butrflynet,
True and why would any one need to go by way of Mexico carrying or not carrying a bio weapon?
You could mail/ship a bio weapon in a small box and getting your people in by traveling on normal airliners would be better then crawling by way of a tunnel.
Europeans have no problem entering the US and there are one hell of a large Muslin population in those countries.
The English suicide bus/subway bombers was second generation English citizens who would had have no problem entering the US legally.