The woman, who is in her 70s, told the Dallas Morning News that Dial threatened to harm her family if she didn't take Bobbi Parker, the warden's wife, on errands.
Parker has told authorities a similar story; that she stayed with Dial because she feared he would harm her family. Parker was abducted by Dial in 1994 when he escaped from an Oklahoma prison.
"I knew the kind of threats she was living under for herself and for her family, because, damn it, I was living under the same kinds of threats," said the woman, who has known Dial since she was one of his teachers at a Houston-area high school more than 40 years ago.
The woman told her story to the newspaper on condition that her name not be published.
"The people that blow their heads about, 'Oh, she could've gotten away.' They don't know him."
She said she still fears Dial and his claims of underworld ties and his threats to hurt her loved ones.
Police acting on a tip arrested Dial on April 4 at a chicken farm near Center, Texas, where the couple lived and worked. Parker has since been reunited with her husband and her two daughters, who were 8 and 10 when she disappeared from the prison grounds in Granite in southwestern Oklahoma.
The schoolteacher said she regularly accompanied Bonnie Parker on shopping trips. She said Dial would dictate a grocery list that always began with beer, cigarette tobacco and jug wine.
The women were given a strict timetable for the trip. Dial always took whatever change was left over from Parker when they returned.
The schoolteacher described Dial as a troubled student she had tried to help. Intermittently over the years that followed their meeting in high school, the teacher helped Dial in response to threats against her family.
In 1999, she said, some five years after Dial escaped, the killer called her "out of the blue" and summoned her to a farm where he was then living with Bobbi Parker.