What Costs More? The Death Penalty or Life in Prison?

This link tells about a death penalty vs. life in prison issue in Yakima, Washington. The issue is: does the death penalty or life imprisonment cost more? In a death penalty case; if you add up the prosecution costs and the defense costs, the cost is $1,028,700 more than non-death penalty cases.
http://www.kndo.com/story/15519792/what-costs-more-the-death-penalty-or-life-in-prison