A former paramilitary leader, accused by human rights groups of leading death squads in the 1990s, was acquitted on Tuesday of a 1993 murder in a one-day trial that was conducted largely after midnight and that brought harsh criticism from human rights activists.

In a verdict reached around dawn after a trial that began Monday, Louis Jodel Chamblain was found not guilty of the murder of Antoine Izmery, a pro-democracy activist and businessman. Prosecutors charged that Chamblain and accomplices, including former Port-au-Prince police chief Jackson Joanis, killed Izmery because he was a key supporter of former president Jean-Bertrand Aristide.

The prosecution called eight witnesses during the jury trial, but only one appeared, and that witness said he knew nothing about the case, the Associated Press reported, quoting Viles Alizar of the National Coalition for Haitian Rights. He said two defense witnesses showed up but offered few details.

The acquittal of Chamblain is one of the first significant acts by the new U.S.-backed interim government of Prime Minister Gerard Latortue. It was installed following the ouster in February of Aristide, who departed the country under pressure from U.S. diplomats after a three-week armed uprising.

Chamblain was a key leader in the rebel uprising against Aristide. Earlier this year, he and several other former military leaders returned from years of exile in the Dominican Republic and the United States, vowing to kill Aristide or chase him from power.

Chamblain was second in command of a notorious paramilitary group, the Front for the Advancement and Progress of Haiti, or FRAPH, that was formed by military leaders who overthrew Aristide in 1991, seven months after the former priest became the nation's first democratically elected president. Human rights groups describe FRAPH as a death squad that killed several thousand Aristide backers over the next few years.

In 1994, the United States sent about 20,000 troops to restore Aristide to power, ousting the military dictatorship. Aristide was reelected in 2000.

Chamblain and Joanis, who fled into exile after the 1994 U.S. invasion, were convicted in absentia in 1995 of the killing of Izmery; Chamblain was also convicted in absentia in the 1994 deaths of several Aristide supporters in Raboteau, a slum whose residents were loyal to Aristide. Under Haitian law, they were entitled to a retrial. Chamblain is still being held pending a retrial in the Raboteau case; Joanis remains jailed on murder charges in a separate 1994 killing.

"This is a very sad day in the history of Haiti," Amnesty International said in a statement Tuesday, blasting the trial as a "mockery" and alleging that Haiti's interim government had "failed to ensure justice and show its willingness to tackle impunity." The rights group said the trial was hastily called, describing it as "an insult to justice" and to those who were killed.

Some opponents of Aristide said that Chamblain's acquittal was not the result of political taint or weakness, but of a simple lack of evidence. Hans Tippenhauer, who was among business and civic leaders who worked peacefully for years to force Aristide from office, defended the actions of the interim government and said that Aristide and his Lavalas party had brought charges against Chamblain for political reasons.

"Mr. Chamblain was one of Lavalas's worst enemies and they went after him," he said. "But I don't think they ever really had enough evidence to convict him."

Louis Jodel Chamblain had been convicted in absentia of a 1993 murder.