Maurice Chamas

And if he didn't have biological evidence on his side, maybe he'd have gone to prison for B's rape, too.

In David's mind, this is all prologue to the desert murder case.

It shows just how easy it was for him to become a target, just how easy it was for him to lose the benefit of the doubt.

If David's lawyers can't stop the execution, then David will die in 22 days.

Specifically, he'll receive a lethal dose of pentobarbital, which will stop his breathing and eventually his heart.

That might sound clinical, but past executions have been pretty grisly.

There are times when the drugs don't work or don't work quickly enough, and you have men groaning in pain and reportedly feeling like they're drowning, suffocating, or burning.

David's heard the stories.

During his time on death row, more than 400 people have been executed, some of them his best friends in the world.

So all things considered, David is clear-eyed about this and knows the odds are against him.

At the same time, he feels some amount of hope, and that's mainly because of his lawyer, Greg.

When David was first scheduled to be executed in 2009, he was full of hate and anger.

He felt totally alone, like his death was inevitable.

So he says he gave up completely.

He gave away his possessions, his typewriter, even his shoes.

But then Greg won him a stay of execution.

Other guys on the road told David he was lucky to get such a good lawyer.

David says Greg reminded him of Mr. Rogers, someone decent and kind who he could actually open up to.

So now, even though David is facing execution again, he doesn't feel like he's fighting it alone.

What do you expect to happen in the next few weeks?