an eyewitness saw the man flee. 40 minutes later, police had their suspect: carlos deluna. the killer was another man, deluna insisted, another carlos, carlos hernandez. >> maybe one day the truth will come out, and i'm hoping it will. if i end up getting executed for this purpose, i don't think it's right, you know? >> suarez: deluna maintained his innocence at every opportunity, up until texas executed him six years later by lethal injection. prosecutors claimed hernandez didn't exist. but while deluna waited on death row, hernandez was telling people about the gas station murder. he also used the same kind of knife that killed lopez to attack other women, including dina ybanez. >> carlos was bragging about the other one he did at the gas station. because somebody else was arrested, he will call him his tocayo, because he got away with it. somebody else was paying for something he didn't do. >> suarez: a tocayo is a person who shares your first name. carlos hernandez died in prison in 1999. now a 430-page report published by columbia law school professor james liebman and

that man is carlos deluna. on the right is carlos hernandez. ad a tough time telling them apart. deluna was convicted and executed for the murder of wanda lopez. despite the apparent confessions from carlos hernandez that he was the real killer. the stories and missteps by investigators explored in great detail in columbia human rights law review. joining us is james leadman who led this investigation published this 400-page report. wow. i spent yesterday reading so much into this. my first question was, you and all of these different students, 23 years after the execution, what got you involved in this detective work to begin with? >> i had published a study in early 2000s that showed courts were finding error in capital cases. a lot of people said maybe that just shows courts are doing their job. we decided let's look into some of these cases and see if there was a real risk that there was the worst kind of error that we worry about, execution of the innocent. we started looking at texas cases that put people on death row and got them executed