Extract the answer to the question from the following context. Question: What killed the bomber? Context: On April 19, 1995, the Alfred P. Murrah Federal Building was destroyed by a fertilizer bomb manufactured and detonated by Timothy McVeigh. The blast and catastrophic collapse killed 168 people and injured over 680. The blast shockwave destroyed or damaged 324 buildings within a 340-meter radius, destroyed or burned 86 cars, and shattered glass in 258 nearby buildings, causing at least an estimated $652 million worth of damage. The main suspect- Timothy McVeigh, was executed by lethal injection on June 11, 2001. It was the deadliest single domestic terrorist attack in US history, prior to 9/11.
A:
lethal injection