By Ebong Udoma

HARTFORD, Connecticut (Reuters) - The governor of Connecticut on Wednesday signed into law a repeal of the death penalty, making it the fifth state in recent years to abandon capital punishment.

Democratic Gov. Dannel Malloy signed the legislation without fanfare behind closed doors, saying in a statement it was "a moment for sober reflection, not celebration."

With the law, which replaces the death penalty with life in prison without the possibility of parole, Connecticut joins 16 other states and the District of Columbia that do not allow capital punishment.

Illinois, New Mexico and New Jersey all voted to abolish the death penalty in recent years, and New York's death penalty law was declared unconstitutional in 2004.

The repeal in Connecticut applies only to future sentences, and the 11 men on its death row now still face execution. However some legal experts have said defense attorneys could use the repeal measure to win life sentences for those inmates.

They include two men convicted of a grisly home invasion attack in 2007 that killed a mother and her two daughters. The only survivor, Dr. William Petit, who lost his wife and two children, had spoken out against the repeal.

About 30 family members of murder victims, clergy and anti-death penalty activists were in the governor's office for the signing.

"Some people were in tears when it was signed, and they were very thankful to the governor," said Ben Jones, executive director of the Connecticut Network to Abolish the Death Penalty, who attended the event.

Opponents of capital punishment said the move in Connecticut fuels momentum for broader abolition.

"We have another state saying, 'We've tried this experiment and the death penalty has failed,'" Shari Silberstein, executive director of Equal Justice USA, said in a statement.

Other state legislatures are considering bills to abolish the death penalty, and Oregon's governor has said he would halt all executions on his watch. A repeal measure has qualified for the ballot in California, home to nearly a quarter of the nation's death row inmates.

Connecticut's Democratic-controlled Senate and House of Representatives approved the repeal earlier this month.

Connecticut has executed only one person, in 2005, since the death penalty was reinstated in the United States in 1976, according to the Death Penalty Information Center. The executed convict, Michael Ross, had abandoned his appeals.

Calling capital punishment "one of the most compelling and vexing issues of our time," the governor said he came to oppose capital punishment while working as a prosecutor.

"I learned firsthand that our system of justice is very imperfect," he said. "I came to believe that doing away with the death penalty was the only way to ensure it would not be unfairly imposed."

He also cited what he called its "unworkability."

"The people of this state pay for appeal after appeal, and then watch time and again as defendants are marched in front of the cameras, giving them a platform of public attention they don't deserve," he said. "The 11 men currently on death row in Connecticut are far more likely to die of old age than they are to be put to death."

(Additional reporting by Mary Ellen Godin, Editing by Ellen Wulfhorst and Doina Chiacu)