I have done a fair amount of reading about the case of Cameron Todd Willingham. He was a man who was executed in Texas for, according to Texas, killing his three daughters. It appears rather clear that, at the very least, there was reasonable doubt that Willingham was innocent. But Gov. Rick Perry, and the execution system he oversees, executed him anyway, apparently not even bothering to read the strong critique of the evidence against him.
The case is best summarized in this New Yorker article. Being a New Yorker article, it's fairly lengthy, but I think it's worth it, particularly with Perry being the GOP frontrunner.
If not, the basic summary is that he was convicted of setting a fire in 1991 which killed his 1 year old twins and 2 year old daughter. The main evidence against him were patterns in the burned house which suggested "puddles" of accelerant (e.g., lighter fluid), as well as marks that indicated more than one source point for the fire. These analyses of the burn patterns is not based on any science, and instead were based on practices handed down from generation to generation of fire investigators. A psychiatri st who pretty much made his living "diagnosing" murder suspects as sociopaths, and who has since been expelled from the American Psychiatric Association, labelled Willingham as such based on an Iron Maiden poster in his house. He was convicted and sentenced to death, despite there being no motive given besides his supposed mental illness, and no evidence besides the non-scientific analysis of the burn patterns.
Just before Willingham was executed, his case was reviewed by Dr. Gerald Hurst, a fire investigator who actually (gasp!) uses scientific methods. He reported on the advances in fire investigation since the 1991 fire. It had since been discovered that accidental fires can form the same patterns (puddles, apparent multiple starting points) as those found in the Willingham house. He gave his report to Perry's office and the clemency board. Internal e-mails show no evidence that anyone in the Governor's office or on the board even read Hurst's report. He was executed (or, if you prefer, murdered) by Texas on February 17, 2004.
Since his death, there was a state panel set up to investigate the use of forensic investigation in Texas. The panel hired another fire investigator to look at how arson cases were investigated in Texas, and he came to similar conclusions as Hurst. Just days before the panel was set to publish its conclusions, Perry removed several of its members and appointed an ally to run the panel. Since then, the panel has assigned the Willingham case to a sub-committee, which allows its hearings to be closed to the public. They have also moved their full meetings to obscure, hard-to-reach areas of the state to discourage reporters from attending.
Rick Perry is the frontrunner in his party's race for the White House. His record, policies and personality have been the focus of the last couple Republican debates. He talks proudly on the campaign trail of the use of executions in his state; he has presided over 235 executions, including Willingham's, in his time in office. If it is true that his state executed an innocent man on his watch, that should disqualify him in the eyes of voters. Hopefully the moderator at an upcoming debate, or anywhere else during the campaign, will have the guts to ask him about it.