Man Testifies He Had Affair With Murder Victim : Trial: A school official tells of his relationship with Janet L. Overton before her death. Her husband is accused of killing her, and prosecutors want to establish a motive.

A high-ranking South County school administrator testified Monday that he had had a long-term sexual relationship with Janet L. Overton before her apparent murder by cyanide poisoning in 1988.

William F. Dawson, an assistant superintendent of the Capistrano Unified School District, told a Superior Court jury that over a six-year period in the 1980s, he and Overton would secretly meet at hotels, motels and in vehicles, including his pickup truck and her van, to have sex.

The testimony by the 61-year-old Dana Point man is a key element in the prosecution’s case against murder defendant Richard K. Overton, 64, who is accused of giving his wife a fatal dose of cyanide. Deputy Dist. Atty. Christopher J. Evans contends that Overton suspected his wife of having affairs with Dawson and with other men, that he hated her because of them, and that he poisoned her to “satisfy his hostilities.”

On Monday, Dawson, in short, succinct answers, admitted that he had not been forthright about the affair when homicide detectives first interviewed him after Janet Overton’s death.

“I preferred no one knew,” said Dawson, who is married. He said he feared news of the affair might cause him to lose his wife and his job.

But after a week of mulling the issue over, Dawson said, his “conscience was bothering” him and he called investigators to tell them about his relationship with Janet Overton.

He said he and Janet Overton, a Capistrano Unified school board trustee, first had sex in 1981 while in San Francisco on unrelated business trips. The affair became more intense in the mid-1980s, he said. But in 1985, a relationship they had tried to keep discreet apparently was discovered. That year a flyer was distributed in Dana Point charging that Janet Overton was having affairs “with married men” from the school district and urged that people not vote for her when she came up for reelection.

The district superintendent confronted Dawson with the flyer and told him that if he was having an affair with her to end it, Dawson said. Prosecutors have suggested that Richard Overton is the author of the flyer.

Despite his boss’s warning, Dawson continued the affair for several more years, he testified.

During his direct examination, Evans pointedly asked Dawson about details of the affair.

“During the height of this relationship, were you in love with her?” the prosecutor asked.

“I wouldn’t say that,” Dawson replied.

“Did she tell you she was with you?” Evans asked.

“Yes,” Dawson said.

Dawson said the relationship ended about 1987, about the time that she started developing painful sores, rashes and lesions throughout her body. Prosecutors allege that the 46-year-old woman was ill because her husband had been chronically poisoning her with another substance before he administered a fatal dose of cyanide.

Dawson said the affair ended because of Janet Overton’s health problems and because she had become a close friend to his wife and had begun to feel guilty about the sexual relationship.

After they stopped their affair, Dawson and Janet Overton remained close friends and saw each socially quite often, Dawson testified. In fact, on Jan. 24, 1988--the day Janet Overton died--she had plans to go whale watching with Dawson on his boat.

On cross-examination, the defendant’s attorney, Robert D. Chatterton, attempted to cast doubt on Dawson’s testimony, suggesting that Dawson could have had more to hide than just an affair.

Chatterton alluded to allegations his client made in a tape-recorded interview with investigators. In that interview, Overton said his wife had told him she may have discovered some financial improprieties at the school district linked to Dawson. In court Monday, Chatterton asked Dawson about his assets, including a 49-foot boat and property he owns in Seattle.

Dawson denied any wrongdoing, saying he had made money in real estate before joining the school district.

For the prosecution, Dawson’s testimony appeared to corroborate some entries in what Evans has labeled “the loathing diaries” that Richard Overton kept on his wife’s activities.

The diaries, which investigators seized, show that Richard Overton meticulously recorded his wife’s activities, including alleged affairs, and the whereabouts of what Richard Overton called her “seduction gear”--condoms, vibrators and other sexual aids.

Several diary entries refer to Dawson and his boat.

Outside the courtroom after Dawson delivered his testimony, Richard Overton, who remains free on $250,00 bail, reiterated that he is innocent. “Everything I told investigators was 100% true. . . . I never hurt Jan, never harmed Jan, and I never administered any poison.”

The trial is expected to resume today with testimony from Overton’s first wife, Dorothy Boyer, who claims that her ex-husband had once tried to poison her nearly two decades ago.