More than two decades after the US state of Texas executed Carlos DeLuna, an investigative study has revealed that he was in fact innocent.
DeLuna was put to death in 1989 for stabbing and killing a petrol station cashier, Wanda Lopez, in 1983.
Now a team from Columbia University claim to have proven DeLuna's innocence. James Liebman, a law professor, and his students say DeLuna's conviction was the result of a poor police investigation, unreliable eyewitness testimony and a weak defence.
Their report concluded that the murderer was Carlos Hernandez, a man who bore a striking resemblance to DeLuna.
Over the last two decades support for capital punishment in the US has been on the decline.
Nonetheless, despite the work of many groups that have raised questions about the fairness of the American justice system, around 60 per cent are still in favour of the death penalty.
Today, there are more than 3,200 people on death row. So far this year, 18 people have been executed.
But the number of death sentences is dropping every year, and more than a dozen US states have now abolished capital punishment.
Death penalty opponents say there is no way to know how many innocent people have been executed in the US.
Over the last 40 years, more than 130 have been released from death row.
Source: Aljazeera, May 18, 2012