One of 10 women on death row in Texas won an appeal Wednesday that will result in a life prison sentence after her lawyer argued prosecutors improperly withheld evidence about comments made by their key witness from her original punishment hearing.

Chelsea Richardson, 27, was convicted of masterminding the slayings of her boyfriend's parents so he could inherit their $1.56 million estate. She was 19 at the time of the December 2003 killings.

Her appeal focused on what her attorney, Robert Ford, said was a prosecutor's failure to give Richardson's trial lawyers notes from a psychologist that suggested another woman masterminded the plot to kill Rick and Suzanna Wamsley of Mansfield, about 20 miles southeast of Fort Worth.

According to the notes, the other woman, Susana Toledano, told the psychologist she was "more guilty than either of them," referring to Richardson and her boyfriend, Andrew Wamsley, that she "did wrong" and "probably could have prevented" the killings.

Toledano — a longtime friend of Richardson's who was the key witness in the prosecution case — took a plea deal from prosecutors to avoid a possible death sentence and testified against Richardson and Wamsley, who also was convicted at trial. Wamsley and Toledano are both serving life prison terms.

Tarrant County prosecutors didn't dispute that the material from the psychologist who interviewed Toledano was withheld, but argued that the notes would not have changed the outcome of the jury's decision to send Richardson to death row.

Ford contended that the notes pertaining to the key witness in the prosecution case did affect the punishment phase of Richardson's trial.

Testimony showed the slaying of the couple at their home was at least the third attempt by the three to kill them. Rick Wamsley, 46, was shot in the head and the back, and stabbed 18 times. His wife, 45, also was fatally shot in the head, then stabbed 18 times.

Ford said he was reviewing the court transcript of Toledano's testimony at Richardson's trial and found that under prosecution questioning she talked about being interviewed by a psychologist. Notes from that interview, however, never were made available to Richardson's defense team. Ford then obtained the 11 pages of handwritten notes from the psychologist.

A judge from another county was appointed to hear the appeal and recommended a new punishment to the Texas Court of Criminal Appeals, which acted on the case Wednesday.

Ford said he told prosecutors, "All I want is to get her off death row and a life sentence." The district attorney's office checked with relatives of the victims "and we came to an agreement," he said.

Tarrant County prosecutors agreed to not seek the death penalty, meaning Richardson will get life and become parole eligible after 40 years. She arrived on death row in 2005 and her time there will count toward her parole eligibility, Ford said.

"It's the way things worked out," Chuck Mallin, a Tarrant County assistant district attorney, said Wednesday. "Pursuant to the agreement, we're going to waive the death penalty."

Ford said he was elated to be able to get someone off death row.

"It's great," he said. "Oh man, it's a good day because it's over. Really, it's taken five years."