Executions in Texas also were down in 2010. Seventeen people were put to death, the lowest total since 2001.
Death sentences nationally have ranged from a high of 328 in 1994, to a low in 2009 of a little more than 100. Harris County, which typically leads the nation in death sentences, condemned two people in 2010.
Harris County District Attorney's spokeswoman Donna Hawkins said the county has averaged two death sentences annually since life without parole became an option.
"It shows that Texas and the rest of the country are moving away from the death penalty, even in Harris County," Houle told the Houston Chronicle.
DNA testing, which has led to the exoneration of more than 40 Texas inmates wrongly convicted of serious crimes, has also eroded support for capital punishment, said Richard Dieter, the director of the Washington-based Death Penalty Information Center.
"It's not that people are all or nothing about the death penalty," Dieter said. "They just have this growing sense of uncertainty. It's a slow wearing away of confidence ... a feeling that it is just too risky."
Supporters of the death penalty point out there are fewer killers eligible for execution. The Supreme Court has prohibited the execution of mentally disabled offenders and those who were younger than 18 when they committed their crimes.
Prosecutors said lengthy sentences for violent criminals and programs to lower recidivism have contributed to the decline in death sentences. They also said there is frustration over death sentences that never are carried out or take decades to happen.
"Twenty-five years later, mothers and sons and daughters of victims are still waiting," said Scott Burns, executive director of the National Association of District Attorneys. "It's the old cliche about justice delayed is denied. For a number of states, the death penalty means we'll talk to you in 25 years and see where we are."