The federal government pursued the death penalty against Brian Patrick Regan in 2003. The jury decided against the punishment, however, and is now serving a life sentence without parole.
Him or the Jury?
The prosecuters asked the jury to choose the death penalty but they declined to do so.
He had also made an offer to foreign governments to sell the information, and judging by the fact that he was carrying classified documents with him when he was arrested, I'd say that he planned on acting on those offers. By contrast, AFAIK Snowden has made no such offer and has not talked with the Chinese government.
I agree that what Regan attempted to do was far worse than what Snowden did. It's not even in the same category. I was just pointing out that the feds did pursue the death penalty in this case despite not pursuing it in the Hanssen case.