Published: Nov 22, 2010 7:48 PM EST
Updated: Nov 22, 2010 4:48 PM EST

TAMPA, Fla. (AP) - An expert says that although DNA evidence has freed a dozen people from Florida prisons, there are likely more than 200 innocents still locked away.

Gary Wells, an expert on eyewitness testimony, figures that's because DNA evidence is available in only about 5 percent of criminal bases, mostly sexual assaults. So for every DNA exoneration, he says, "you have to minimally multiply it by 20."

The Iowa State University psychologist told the Florida Innocence Commission that eyewitness mistakes is the No. 1 contributor to faulty convictions that are later overturned by DNA testing.

The 22-member Innocence Commission, meeting in Tampa Monday, is
charged with finding ways to keep innocent people out of prison.