Texas inmate David Ray Harris went to his death with no excuses on June 29.   ``Sir, in honor of a true American hero: Let's roll,'' Harris said when asked if  he had a final statement. By echoing the words of a passenger before he and  others attacked the hijackers of Flight 93 on September 11, 2001, possibly   causing the jet to crash before reaching its intended target in Washington,   Harris apparently wanted to sound heroic.

But Harris was no hero. He was  a cold-blooded killer who also almost caused the execution of Randall Dale  Adams, an innocent Ohioan Harris helped frame for the first of two murders we  know Harris committed at a young age. Only because Adams had good trial  attorneys whose objections to the actions in the kangaroo court that convicted  him and an appeals attorney who exploited those objections to the hilt was  Adams' life saved by the U.S. Supreme Court three days before his scheduled  execution in 1979.

Prosecutors asked that the Ohioan's sentence be  commuted to life in prison rather than face the possibility of retrying Adams,  who had no prior record, for the 1976 murder of Dallas police officer Robert  Wood. They knew Adams would probably walk free if tried again for a murder it  was increasingly apparent he did not commit, so they settled for letting him rot  in jail instead of frying him.

When Erroll Morris' acclaimed 1988  documentary, The Thin Blue Line, finally ripped the evidence against Adams to  shreds and ended his film with a dramatic statement from Harris in which he  essentially confessed to the crime, international public pressure finally forced  the Texas court system to release Adams, who flew back to Columbus a hero for  enduring his nightmare with dignity, faith and courage.

But Harris  wasn't "Texecuted" for the murder of Officer Wood. His life was ended for the  1985 murder of Mark Mays after Harris tried to abduct Mays' girlfriend.  

And therein lies the second outrage that resulted in putting Adams on  death row for a murder he didn't commit. By framing Adams and letting Harris   literally get away with murder, then-assistant district attorney Doug Mulder,   several dishonest Dallas detectives and witnesses looking for a deal or their 15   minutes of fame gave Mark Mays a death sentence as well as the innocent Adams.  

Mulder had never lost a capital trial, and he wasn't going to start then  by letting the non-Texan (which is almost a crime itself in Texas) off the hook.   To bolster the perjured testimony of Harris, the Dallas police and shameless   "eyewitnesses" who saw nothing, Mulder called in his bug gun: the late James   Grigson, who was called "Dr. Death" for his prosecution-friendly testimony in  hundreds of death-penalty cases. The folksy, always-certain psychiatrist helped  persuade juries that almost every defendant he testified about after a cursory  on nonexistent examination would undoubtedly kill again if given the chance.  

The danger of Grigson's testimony was laid bare for the world to see in  The Thin Blue Line. The movie documented how Grigson testified that the   soft-spoken Adams was an "extreme sociopath" who would kill again, even though  Adams had never been in trouble in his life, just as he has never been in  trouble since his release in 1989.

The same couldn't be said for "Dr.  Death." The psychiatric hit man was twice reprimanded by the American  Psychiatric Association -- once for improperly using the results of a competency  test against a defendant during the punishment phase of his trial and then for  claiming he could predict with absolute certainty how dangerous a defendant he  had never examined would be in the future. As more questions about Grigson's  ethics came to the fore, the association finally expelled Grigson from its ranks  and the Texas Society of Psychiatric Physicians followed suit.

The  biggest culprit in the vicious, dishonest prosecution of Adams that freed Harris  to kill again was Doug Mulder. Mulder, unlike murder victim Mark Mays, is alive  and well and making lots of money -- as a criminal-defense attorney, of all  things.

As sad as Mark Mays' needless death was, it was not all that  unusual. It is conservatively estimated that more than 10,000 Americans are  convicted of serious crimes they did not commit each year. That means the person  who did commit the crime got a "get-out-jail" card that frequently persuades  them that they know how to beat the system and they keep on trying -- often  committing more murders, rapes, robberies or other serious felonies before the  law or time finally catch up with them.

If the mistakes that led to  wrongful convictions were honest ones made after a painstakingly thorough  investigation, it cold be argued that is the price we have to pay in a  high-crime society full of fallible people.

But an Innocence Project  analysis of what cased the erroneous convictions of the first 70 people  exonerated by DNA testing found that a significant percentage of wrongful  convictions occurred because of doctored, planted or misinterpreted evidence;  false confessions squeezed out of suspects by psychological manipulation, lies  about evidence and mistreatment that stops just short of physical abuse; false  testimony by frequently discredited jailhouse snitches and other witnesses;  scientifically discredited but still permitted forensic evidence, including  microscopic hair comparison matches; prosecutorial misconduct; poor work by  defense attorneys; police misconduct; and -- the biggest cause of all --  mistaken identifications.

Proposals backed by sound science could help  eliminate most of these causes of erroneous convictions, but prosecutors and  police are loathe to admit that the system needs fixed. As long as they resist  reform, more innocent people will go to prison and more serial criminals,  killers and rapists will be allowed to commit more crimes, and more Mark Mayses  will be victimized by more David Harrises. And that's the biggest crime of all.  

Martin Yant is the author of Presumed Guilty: When Innocent People  Are Wrongly Convicted and four other books. He is also a licensed private  investigator whose investigations have helped exonerate 10 inmates, two of whom  were originally sentenced to death.