You’ve likely seen this report about the women’s winner at Chickamauga this past weekend being DQd because her finish time was a virtual impossibility given her 13.1 split. Read here and let me know what you think.
This was my third marathon in 2010, It is 2 loops around the Chickamauga Battlefield park, on a partially closed course with lots of opportunities to manipulate your time. This is a small race with not a lot of course marshaling, or timing mats.
Battlefield Marathon Winner Disqualified
Another article is here
This Running Life 
I read the thread about this on Let’s Run. I think from her previous times, it’s highly unlikely she ran that time.
Had she run a marathon anywhere close to a 2:55 or a half close to 1:20 at any point, then her story would have more credibility to me. However, 4:25 to 2:55 is an ENORMOUS and totally unbelievable PR, regardless of how much training she did.