New Mexico Governor Bill Richardson has signed legislation abolishing the death penalty in the US state.
Mr Richardson, a former supporter of capital punishment, said it had been the "most difficult" decision of his political life.
He said he had decided to approve the legislation because DNA evidence had shown that innocent people had been sentenced to death in the past.
New Mexico joins 14 other states that have done away with capital punishment.
It is only the second to do so since the US Supreme Court reinstated the states' power to impose the death penalty in 1976.
New Jersey was the first, in 2007.
New Mexico's repeal legislation will take effect in July and will apply only to crimes committed after then.
"Faced with the reality that our system for imposing the death penalty can never be perfect, my conscience compels me to replace the death penalty with a solution that keeps society safe," the Democratic governor saidThis article is from the BBC News website. © British Broadcasting Corporation