Death row houses the nation's most ruthless and violent killers. But despite being sentenced to die, most of the condemned will never make it to the death chamber.

From Florida's electric chair to California's lethal injection, endless strings of appeals and legal delays mean most death row inmates will die of natural causes in prison, rather than at the hands of the state.

"It doesn't take anything other than simple math to figure out that if we're executing one person a year and adding dozens that go on death row, we're going to exceed our capacity to hold individuals on death row and we're going to have to do something about it," said Bob Martinez of the California Department of Corrections. 

California's Corrections Dept. houses more than 600 prisoners on death row -- more than any other state. Now, two more names could be added to the list.

David Westerfield, on trial for the kidnapping and murder of 7-year-old Danielle Van Dam, is one of them. Then there's Alejandro Avila, charged with the abduction, sexual assault and murder of 5-year-old Samantha Runnion. 

Both could face the death penalty if convicted, but neither is likely to be put to death. 

"We've had capital punishment on the books now for [25-27] years and it hasn't stopped the Westerfields and Avilas," said Mike Farrell, president of the San Francisco-based Death Penalty Focus, a nonprofit supporting getting rid of capital punishment. "Capital punishment is not a deterrent."

Opponents of the death penalty point to crime statistics to show that capital punishment doesn't work. But former California Attorney General Dan Lungren argues that capital punishment can't deter if no one ever gets executed.

Since the death sentence was reinstated in 1976, the U.S. death row population has grown from 400 to almost 4,000. And while all agree those convicts deserve every chance to prove their innocence, critics ask why it seems the only thing dying on death row may be the death penalty itself. 

Adam Housley joined Fox News Channel (FNC) in 2001 and currently serves as a Los Angeles-based senior correspondent.