Every part of a death penalty case is longer and requires more legal time, since capital punishment is on the table, Dieter said.
Two lawyers are usually assigned to each side of the case, and in general, the jury selection takes longer. There are also usually two trials in death penalty cases -- one to determine guilt and one to determine sentencing.
Once defendants are sentenced to capital punishment, they may still cost more than inmates who receive sentences of life-without-parole, even though their imprisonment may be for a shorter period of time. Death penalty inmates are normally held in single cells and in solitary confinement. They require high security and more guards.
But the view that the death penalty is a poorly allocated expense isn't shared by everyone.
A Georgia study conducted by the National Institute of Corrections in 2004 found that the state's aging inmate population cost three times that of a younger inmate population in health care costs.
"Life in prison is more expensive than the death penalty when you're paying for health care for aging life-with-parolers," said Diane Clemence, spokeswoman for Texas pro-death penalty group Justice for All.
Clemence said death row inmates wouldn't cost states as much, since they shouldn't be staying in the prisons into old age.
"It's not an apples-to-apples cost issue," she said. "It's a moral issue and it's an issue about justice and safety."
Rushford also cited the health care costs of keeping more inmates with life sentences.
"What if they needed a heart transplant?" he said. "Then taxpayers would be paying millions for an inmate to get a new heart. Would people think that was just?"
Dieter said that although he had testified for many state legislatures on the costs of the death penalty, the arguments for and against capital punishment remain moral. However, in light of the recession, the cost is making the public and state legislatures more open to repealing or abolishing the death penalty, he said.
"The public feels the budget and the economic recession directly," Dieter said. "When it affects your paycheck, you say, well what other things can be cut? I support the death penalty, but if we're spending $10 million a year and getting one execution a year, you may be able to let it go."