How, exactly would you determine the difference between someone who has been wrongly convicted and is actually innocent as compared to someone who has been rightfully convicted and is guilty? You would have to determine that to be able to say who gets how many appeals. Both of them have been pronounced guilty...that is why they are in prison. Without the appeals process applied universally, you have no way of discovering who was wrongfully convicted.
Someone who is innocent would have holes in their case. They wouldn't have everything. DNA evidence doesn't get messed up, if it does the scientist that did it has the chance of being sentenced too, so if there is DNA evidence that not only connects the person but is on the scene in a particular place that is not possible to mistake (aka in a women from being raped) then they are rightfully guilty. Its all facts. If the courts don't wait for all of the holes to fill then that sucks for the person, but they should take in to account that they cannot convict someone guilty if they are missing prime evidence. I say if there are holes in the case at all, postpone the trials finish till a later time and till the holes are filled. If they can't fill them then they shouldn't get the death penalty. But for Belia's case they waited 3 years to trial him till every hole was filled--that is how it should be done.
In my opinion if there is DNA in a place that could not be falsely placed then they are guilty and will be rightfully guilty. but i can tell your not gonna take any answer except "there is no way to really know." I think that anyone that gets themselves in a situation of being wrongly accused must have been somewhere they shouldn't have, so they took their chances and now they have to either come up with the proof or face reality.
The guilty criminals should not be given more appeals just so the wrongly accused can keep appealing. they obviously were in the wrong place or did something to be wrongly accused.