Cameron Todd Willingham, who went by Todd, with his wife, Stacy. The couple's three children died in a fire Dec. 23, 1991, at the family's Corsicana, Texas, home. Willingham was accused of arson and tried for murder.<br>

Todd Willingham with wife Stacy, daughter Amber and twin daughters Karmon and Kameron. Journalist David Grann told the story of Willingham's conviction on arson and murder charges -- and eventual execution -- in the Sept. 7, 2009, issue of New Yorker magazine. The article gained wide attention and renewed interest in the case and the fairness of the application of the death penalty.

The Willingham girls: Amber, 2, and twins Karmon and Kameron, 1. "I just don't understand why anybody would take them, you know?" Willingham told investigators in the arson case, according to Grann. "We had three of the most pretty babies anybody could have ever asked for."<br> <b>Watch the full story tonight on "Nightline" at 11:35 p.m ET</b>

On Dec. 23, 1991, a fire consumed the Willingham home, killing Amber, 2, and twins Karmon and Kameron, 1. Willingham, who said he was home napping at the time, ran from the house, escaping physical harm. After an arson investigation, he was arrested, tried and convicted of murder. But as his execution date drew closer, questions about the reliability of the arson evidence emerged.

Fire investigators found what they said was evidence of arson. Later, their testimony would be challenged.

After the fire that killed their three daughters, Todd and Stacy Willingham were divorced. She became convinced that he was guilty, although she later would change her mind. Amber, Karmon and Kameron Willingham were buried in Corsicana, Texas.

Todd Willingham on death row, during a visit by his father and stepmother. Willingham refused to plead guilty, though he could have avoided the death penalty by doing so. He maintained his innocence to the end. As Willingham's execution date in February 2004 approached, an arson expert's review of the case found no evidence of arson. "The people who investigated the fire did not understand the behavior of fire," the expert, Gerald Hurst, recently told ABC News. A Texas board of pardons took the new information into account, but opted not to act.

Todd Willingham on the morning of his execution by lethal injection. He was asked if he had any last words. "The only statement I want to make is that I am an innocent man convicted of a crime I did not commit," he said. "I have been persecuted for 12 years for something I did not do. From God's dust I came and to dust I will return, so the Earth shall become my throne."