No exact proof, but unverifiable sources (wikipedia
http://en.wikipedia.org/wiki/Lottery ) and a few others point to her having cracked the distribution algorithm.
" It was speculated that there was actually a pattern to where and when the winning tickets were sold, and that Professor Ginther had figured out this pattern"
She also seemed to be requesting stores buy certain types of big ticket cards etc.
It of course would not be impossible for someone to win that many big jackpots that many times buying large numbers of tickets(she bought something like 3000+ a year), but they estimate the odds to be:
"The fourth time she won the lottery, AP wrote that her chance was 1 in 18 septimillion, which 1 in 18,000,000,000,000,000,000,000,000 (24 zeros in front of 18)."
I'm not sure exactly what, but it seems like she figured something out. She has never done any public interviews or anything(i wouldn't either if i figured something out).
She now lives in vegas....