Remember the Islamic Movement of East Turkestan (the Chinese al-Qaeda) that the US added to the terrorist list a few weeks back? This could easily be them, as they've carried out suicide attacks before.
Five members of the Oregon Cell went to China beginning in October of 2001 enroute to Afghanistan.
It was about this same time that Muhammed and Malvo took up residency at the shelter.
Things to ponder: April 23, 2001.
John Williams changed his surname to Muhammed AND the first pair of hijackers entered the United States.