STARKVILLE, Mississippi (Reuters) - Mississippi Governor Haley Barbour pardoned four convicted murderers who worked at the Governor's Mansion, releasing them from prison in the final days of his term in office, state officials said on Monday.

In all, Barbour pardoned four men convicted of murder and another convicted of burglary and robbery, all serving life sentences. In the executive orders Barbour signed, he wrote each "proved to be a diligent and dedicated workman."

A former chairman of the Republican National Committee who considered running for president in 2012, Barbour is due to leave office on Thursday. His office did not return repeated attempts for comment.

The pardoned inmates included David Glenn Gatlin, who was denied parole in December on his conviction for shooting dead his estranged wife while she cradled their baby in 1993.

"He shot her in the head while she was holding a baby. He's a cold-blooded murderer," said Tiffany Ellis Brewer, the victim's sister.

Her family joined Democratic lawmakers at a news conference in the capital Jackson on Monday, demanding limits to the governor's ability to pardon killers.

Barbour issued the pardons on Friday and Brewer said her family learned of them on Saturday when contacted by a victims' advocate organization.

Gatlin was one of five inmates serving life sentences who worked at the Governor's Mansion and were pardoned by Barbour in one of his last official acts before Governor-elect Phil Bryant, also a Republican, takes office on Thursday.

Gatlin had worked at the mansion since November 2009, Mississippi Department of Corrections records show.

The other pardoned inmates were Charles Hooker, a middle school teacher convicted in 1993 of murdering his school's principal; Anthony McCray, convicted of killing his wife in 2001; Joseph Ozment, convicted in 1993 of murder, conspiracy and armed robbery; and another man serving life for burglary and robbery.

Each worked as a trusty at the Governor's Mansion while serving prison sentences. Work by trusties would typically include kitchen duty, waiting tables, cleaning and washing vehicles, said Suzanne Singletary, spokeswoman for the Mississippi Department of Corrections.

Mississippi governors have routinely pardoned inmates, Singletary said, but said she did not have information about how many pardoned inmates were convicted of murder.

(Editing by Daniel Trotta and Greg McCune)

Mochila insert follows ...