Captain America is Killed Off

Captain America is killed off. This is supposed to be a "sign of the times." Who kills off Captain America?

"The superhero was spawned when a scrawny arts student named Steve Rogers, ineligible for the army because of his poor health but eager to serve his country, agreed to a "Super Soldier Serum" injection. The substance made him a paragon of physical perfection, armed only with his shield, his strength, his smarts and a command of martial arts."
- Times Tribune

[via Digg]