Police: FBI probing past of suspect in Oklahoma beheading

(CNN) -- First came word of a woman stabbed. Then screams. Then gunshots.

But the full story of Thursday's gruesome beheading at an Oklahoma food processing plant -- especially why it happened -- is still waiting to be told.

One day later, there are tears for Colleen Hufford, the 54-year-old woman whose head was severed. There are prayers for 43-year-old Traci Johnson, who is in stable condition at a nearby hospital for treatment of "numerous wounds," according to police.

And there are questions about 30-year-old Alton Alexander Nolen, the man who authorities say attacked them both and might have gone after more people if not for the company's CEO, also an off-duty reserve sheriff's deputy, who confronted and shot him twice. Read More