"You can support the death penalty, but would you support it if you knew it cost us police officers?" Stallworth said. "These hundreds of millions of dollars are going to be needed to be spent on things that are more proactive."
But for supporters of the death penalty, cost is not part of the calculation in whether to mete out capital punishment.
Michael Rushford, who heads the Criminal Justice Legal Foundation, said some states' death penalty systems are less cost efficient than others. But he said that abolishing the death penalty shouldn't be a question, since in his view, capital punishment protects society and delivers justice.
Rushford cited the Oklahoma City bombing case as an example of where the death penalty was carried out properly. Timothy McVeigh, a U.S. Army veteran and former security guard, was convicted of 11 federal offenses and sentenced to death after detonating a truck bomb that killed 168 people in 1995. McVeigh was executed in 2001.
Rushford compared the California appeals process for a capital punishment case, which is about 25 years, to other states, such as Virginia, where it is only about six years. If the law enforcement system is reformed to move the process more quickly, the cost could be lessened, he said.
"The [California] system is rigged against a prompt process for, after the determination of guilt, moving the case along," Rushford said. "So the cost is enormous."
He said that the legislatures in many states that spend excess funds on the death penalty aren't giving police and lawyers the power they need to enforce capital punishment.
"The system has been rigged not to enforce the [death] sentence by the opponents of the death penalty, and it's been the opponents who are now holding up the cost of that to say, 'Let's get rid of it,'" Rushford said.
A typical cost per year for the death penalty ranges from $10 million to $20 million in states that have one or fewer executions per year, according to Richard Dieter, executive director of the nonpartisan Death Penalty Information Center. This number does not take into account states that have extreme numbers of executions or death row inmates, such as Texas or California.
"There have been quite a few studies in various states," Dieter said. "And the studies have all concluded that the death penalty is more of a burden on taxpayers than if the same defendant receives a life sentence."
A study by a Duke University economist in 2009 of North Carolina's death penalty costs found that the state could save $11 million a year if it abolished the death penalty.
In 2008, an Urban Institute study of Maryland found that a death penalty trial costs $1.9 million more than a nondeath penalty trial. The study also estimated that the state's taxpayers had paid at least $37.2 million for each of the five executions the state had carried out since 1978.
The Tennessee Comptroller of the Currency estimated in 2004 that death penalty trials cost an average of 48 percent more than trials in which prosecutors seek life imprisonment.
A 2003 legislative audit in Kansas concluded that capital cases are 70 percent more expensive than comparable nondeath penalty cases.
Every part of a death penalty case is longer and requires more legal time, since capital punishment is on the table, Dieter said.