David Cooper Nelson was the first individual to die in the New Mexico gas chamber, and the last person executed as of the web publication of this article (2007).

Warden Harold Cox advised Nelson to take a deep breath of the fumes, and asked whether Nelson had anything to say. Nelson responded, "OK Warden. God be with you." Cooper then remarked to the prison chaplain that he was going home, and, in a scene reminiscent of the execution of Louis Young, was told to "keep praying."

The door was subsequently screwed shut, and cyanide fumes rose about his face at 12:12 AM. Gasping, Nelson expired at 12:20 on August 11, 1960. Upon the witnesses leaving the prison, a prisoner was heard to shout "Are you happy now?" Warden Cox subsequently told reporters that he was proud of the efficiency of the execution.

Nelson was convicted of murdering Ralph Henderson Rainey, a 46 year-old butcher from Santa Monica, CA, who had picked up the hitchhiking Nelson. Rainey’s body was found near Budville, on January 10^th, 1956, and had apparently died within the previous two days by two gunshot wounds to the head.

Nelson’s fingerprints were found in Rainey’s vehicle. Upon being located in Las Vegas, Nevada, Nelson subsequently confessed twice to the killing but later repudiated his confessions. He also confessed to killing two other individuals, John Valente and Kenneth Short, although he also later recanted the Valente confession.

At his first trial, Nelson maintained an insanity defense, but was found sane and guilty. At the second trial, his confessions were disallowed, but with the same end result. Nelson subsequently tried to escape from prison.

Prior to his execution he maintained that he had witnessed a third party kill Rainey. At the last, he requested that the two prisoners in the cells next to his former cell receive special meals after his death, a wish with which Warden Cox said he would comply.