I personally knew a big b/w tegu breeder whose breeding facilities were in Alabama. It was called Agama International, a 7-acre farm which annually produced thousands of lizards of many sorts, including tegus. The breeder passed away in 2008, leaving the facility to his son. It has since been sold to another couple. With the storms/hurricanes/etc. which have occurred in Alabama in the past few years, it is entirely possible that some of his breeding animals escaped. I remember him posting photos of the expired-date turkeys and chickens he'd get free from local supermarkets that he'd thrown (minus the plastic) into the tegus' enclosure after running the birds through a radial arm saw and how they would just chomp them down, bones and all.
“...it is entirely possible that some of his breeding animals escaped....”
I would say that is THE most likely scenario...