''I surely don't know what I would do if a group of people were hauling me off to kill me.''

Sister Helen's account of her experiences with the criminal justice system, as a spiritual advisor to those condemned to death, is a wonderfully sad and disheartening expose of a system where truth does not count - only procedures. In the first chapter she speaks of Roger Coleman, a Virginia coal miner who was executed in Virginia on May 20 1992, because of a procedural technicality.

His rookie lawyer, trying her first capital case, filed Coleman's petition one day late - 24 hours late - and so they took his life.

The two other cases Sister Prejean discusses in ''The Death of Innocents'' -- of Dobie Gillis Williams, a poor black man from rural Louisiana with an I.Q. of 65, accused of rape and murder, and Joseph Roger O'Dell, a white man with a long record, arrested for murder, rape and sodomy in Virginia -- are typical. The evidence against them was not insubstantial, but some of it was inconsistent, some of it suggested other potential killers and much of it was open to question. In both cases, a decent lawyer could probably have gotten them off. A decent lawyer certainly could have saved their lives. As Justice Ruth Bader Ginsburg has said, ''People who are well represented at trial do not get the death penalty.'' Williams's lawyer did not conduct rudimentary testing on blood evidence, failed to object to an all-white jury and offered almost no evidence at sentencing that might have allowed the jury to show leniency. O'Dell foolishly decided to represent himself, though it is hardly clear that the typical court-appointed lawyer would have done better. Once the trials were over, rules of appellate procedure limited the ways the two men could attack their convictions and sentences.

In O'Dell's case, Virginia prosecutors acted shamefully in denying him and his estate the chance to test biological evidence. Had Williams and O'Dell brought their appeals in the Northeast or in California rather than in Louisiana or Virginia, appeals courts would probably have found a way to save their lives. Indeed, O'Dell at one point came within one vote in the Supreme Court of a new sentencing hearing. The decision had nothing to do with the evidence in the case. Instead, the court said that one of its rulings, about jury instructions, did not apply retroactively. It came, that is, too late to help O'Dell. There is something appalling in seeing a man's life or death turn on a 5-to-4 vote. Williams also had the misfortune of being tried too soon. In 2002, three years after his execution, the Supreme Court ruled that the Constitution bars the execution of the mentally retarded.

She is a tough nun. When O'Dell confides that he does not intend to go quietly, she does not try to dissuade him. ''I surely don't know,'' she tells him, ''what I would do if a group of people were hauling me off to kill me.''
Sister Helen Prejean, The Death of Innocents: An Eyewitness Account of Wrongful Executions