[lelio]

In 14 years that the federal death penalty has been in place
What do you have to do to get a federal death sentence? Does that trump a state's law against murder?

[Poohbah]

What do you have to do to get a federal death sentence?

Murder federal law enforcement officers; commit espionage on behalf of a foreign power in matters of nuclear weapons, military cryptographic systems, and military space systems. That's just about it.

[SauronOfMordor]

What do you have to do to get a federal death sentence? Does that trump a state's law against murder?

Killing a federal employee will get you a federal execution, even if the state that it occurred in does not have the death penalty. And perhaps even if, under state law, you would have gotten off under "self-defense".