WASHINGTON - Almost a year to the day after the controversial execution of Troy Davis, another US death row case roiling rights activists is being reopened.

Starting Monday, Reggie Clemons - a black man who has spent 19 years behind bars after being convicted in the murder of two young white women - will attempt to prove his innocence in a highly unusual review of his death sentence by a judge in St. Louis, Missouri.

The hearing, which could last three to five days, follows protests by human rights groups and comes after the 40-year-old's 2009 execution date was stayed.

"It is a checklist of all the most horrible things that can occur in a capital case," said Laura Moye, head of Amnesty International USA's Death Penalty Abolition Campaign.

"This hearing ultimately could determine whether Reggie Clemons will live or die."

The Clemons case bears similarities to that of Davis, also an African-American, who was put to death in the US state of Georgia on September 21, 2011 for the killing of a white off-duty police officer despite doubts over his guilt.

The execution was the country's most high-profile in a decade and prompted an outcry from the European Union and elsewhere.

Clemons was convicted in 1993 of the murder of two sisters - aged 19 and 20 - who drowned in the Mississippi River two years earlier. Circumstances surrounding the deaths are unclear.

Together with three friends, two of whom were black, Clemons was on the Chain of Rocks Bridge spanning the Mississippi River the night the women died.  Also in the vicinity was Thomas Cummins, out for a walk with his two cousins, Julie and Robin Kerry. Cummins was first held responsible for the women's deaths, before accusing Clemons and his friends, according to court documents.

After a trial that human rights organizations said was marred by a number of irregularities, Clemons and his two Africa-American friends were sentenced to death. They have always maintained their innocence.

One of the men was executed in 2005, while a second saw his sentence commuted to life in prison because of mental retardation. Clemons, meanwhile, remains on death row.

The fourth person implicated in the killings, a white male, pleaded guilty and received a lighter sentence in exchange for testifying against his three companions. "We know that mistakes regularly occur in death penalty cases and the innocent are executed," Moye told AFP.

"Troy Davis went to his death in Georgia because the justice system failed to adequately scrutinize the doubts raised about his conviction," she said, adding the case "illustrates all the flaws in the US death penalty system."

- No physical evidence -

Much like Davis, Clemons was sentenced to death largely on the basis of witness testimony and no physical evidence.

For the first time, samples related to the alleged rape of the victims will be presented during the new hearing. Clemons initially admitted to the rape of one of the victims but later retracted his confession. Much like Davis, Clemons was convicted in the murder of whites amid interrogations that he claims were marred by racism and police brutality. "I remember police mainly beating me in the chest, and that was something that scared me a whole lot," Clemons told Britain's Guardian newspaper. "While they were beating me, they were telling me that they wanted me to admit to."

For both Davis and Clemons, activists say the accused were not properly represented during the trial, the investigation was riddled with problems and the defendants faced a largely white jury.

Clemons had an abusive prosecutor who "compared him to a serial killer although he didn't have any criminal record," according to Amnesty.

Following the new proceedings, the judge reviewing Clemons's case is set to make a recommendation to Missouri's Supreme Court, which will ultimately decide whether the prisoner will live or die. All other options to appeal his execution have been exhausted.