09 January 2015 :

Seattle University released the results of a seven-month study into the costs of the death penalty in Washington state and found death penalty cases cost a million dollars more than similar cases where capital punishment is not sought.
The study quantifies extra death penalty cost of 147 aggravated first-degree murder cases filed in Washington state since 1997.
Combining all cost categories, the researchers found the average cost of a death-penalty prosecution and conviction is just over $3 million. Not seeking a death-penalty prosecution and sending a person to prison for life costs the state roughly $2 million.
The future of the death penalty in Washington remains unclear. Last February, Gov. Jay Inslee issued a moratorium on the punishment while he is in office. His term is set to expire at the end of 2016, unless he's re-elected.