Richard and Nancy Lyon

Receipt for poison

Nancy told her father that their marital problems were exacerbated by Richard's addictions to sex and alcohol. Dillard Sr. was pleased with Bill Jr.'s progress after his stay at Sierra Tucson, so he agreed to pony up another hefty fee to have his son-in-law's addictions ministered to at the same facility.

Richard lasted two weeks, and then cut out early for a rendezvous with Gaisford.

In spite of everything — the affair, the lies, and the financial irresponsibility — Nancy continued to open her door when Richard knocked.

He was a convincing groveler, and she was vulnerable.

Not unlike most couples going through a slow-motion breakup, their relationship roiled minute to minute through the fall and winter of 1989.

Richard told confidantes that their sex life had improved in quality and quantity, according to author Gray. Nancy got pregnant but suffered an early-term miscarriage. The Lyons and their daughters traveled as a family to New York at Christmas 1989 and visited Richard's parents in Connecticut.

But a month after Christmas, Nancy used more homespun detective work to determine that her husband had once again gone off with his lover. She ordered him out of the house, and he took an apartment in another Dallas suburb.

No one but Richard knows what was on his mind as he drove away from his family that day.

But one thing is indisputable: On Jan. 24, 1990, he became a regular customer of General Laboratory Supply, a firm near Houston that sells chemicals, including poisons.