These rumours were all over Woodstock from the moment it was announced that Tori was missing. The info didn't have to come from Facebook; it was even in the media. This is from May 14, 2009.
http://www.woodstocksentinelreview.com/ArticleDisplay.aspx?e=1568901
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'm not even sure it was necessarily MTR who told these rumours to TLM. Anyone she was in contact with before and after her initial arrest could have told her. MTR didn't have to know TM or JG to have heard or read the rumours, either. They were rampant and Tara denied them, although she now admits that JG did have a $400 debt. As for the "other" rumour, that, too, was all over town and the internet, with documentation showing what it was based on.
JMO