The South Tower fell at 9:59 a.m. Per the report released by the City of New York which is linked below,
someone called 9/11 22 minutes before then, at 9:37 a.m., from the 105th floor of WTC2 and reported
that "floors beneath him in the 90-something floor had collapsed." Here's the link and the quote appears
at page 46 of it.

http://www.nyc.gov/html/fdny/pdf/mck_report/ems_response.pdf

How does this fit into pre-existing controlled demolition theories?

Angie
911 Truth Movement Musings (Watching the Watchers)
http://www.Angieon911.com