The state charged Allen with first-degree murder and announced that it would seek the
death penalty. Evidence that Leathers had a history of violent conduct, and that she had stabbed a woman to death in
Tulsa, Oklahoma in 1979, was central to Allen's
self-defense argument at her trial. Allen testified that she feared Leathers because of her boasting about the 1979 killing. The defense sought to corroborate this claim with testimony from Leathers' mother, whom Leathers had told about the fatal stabbing. But, the prosecution objected. The court prohibited the introduction of such testimony because it was considered hearsay. The prosecutor depicted Allen as a remorseless liar. The jury found her guilty of first-degree murder and sentenced her to death. During the punishment phase, the prosecutors argued that Allen should be sentenced to death because she had been previously convicted of a felony involving the use or threat of violence; that she was a continuing threat to society; and she committed the murder to avoid arrest or prosecution. The jury found that the first two aggravating circumstances existed in Allen's case. Her defense presented numerous
mitigating circumstance, including a good relationship with her family, good work habits, and her fear of the victim. In the sentencing phase, the prosecution retrieved details about the circumstances of the death of Dedra Pettus, even comparing that earlier crime to Leathers's death. In a 1991 affidavit, Allen's
defense lawyer David Presson stated that after the trial, he learned that when Allen was 15 years old, her IQ was measured at 69, placing her "just within the upper limit of the classification of mental retardation", according to the psychologist who analyzed her. In addition, an examining doctor had recommended a neurological assessment because she manifested symptoms of
brain damage. The lawyer stated, "I did not search for any medical or psychological records or seek expert assistance for use at the trial." A psychologist conducted a comprehensive evaluation of Allen in 1995 and found clear and convincing evidence of cognitive and sensory-motor deficits and brain dysfunction, possibly linked to an adolescent head injury. Of the five members of the
Oklahoma Pardon and Parole Board, three were appointed by Governor
Frank Keating. Keating considered giving Allen a stay based on the narrow issue of whether the Oklahoma Pardon and Parole Board had enough information regarding her education. Allen's attorneys have pointed to her score, a 69, on an IQ test she took in the 1970s, arguing she was in the range of intellectual disability. Prosecutors said Allen testified during the penalty phase of her trial that she had graduated from a high school and received a medical assistant certificate from a college. But they said that, in fact, Allen dropped out of high school at 16 and never finished course work in the medical assistant program. ==Execution==