I need to know how accurate DNA testing is?

I'm writing a paper on capitol punishment, and one of my main points is DNA testing makes it difficult to sentence an innocent person. I know it's accurate, but I need sources that say that. They have to be "scholarly" so now yahoo, google, or wikipedia results. I need a source from an expert that was printed in a JOURNAL

i really need it cuz i researched it on google and stuff and I don't understand a thing.

I have viewed many photos of our Yahoo families lovely animals asking what breeds we think they are. I've recenly learned that we can easily answer theses questions ourselves. You can Google Dog DNA Analysis and explore the many avenues to find out exactly what Fido is made of:) Happy Hunting!