I want to know the answer to the following question:
If prisoners use federal habeas corpus to present evidence that they're innocent, what must the evidence be?
All the background I'm provided with is that "Federal habeas corpus is a species of collateral review, and it is the only way that state prisoners may attack a death sentence in federal court (other than petitions for certiorari to the United States Supreme Court after both direct review and state collateral review).". Is that enough to answer the question?