In August 1990, 29-year-old Mark Peterson was arrested in Oshkosh, Wisconsin. He was charged with raping a 26-year-old woman after they went on a coffee date on June 11 of that year.

When the victim first testified at a preliminary hearing, she said that she had multiple personalities—21 in all, some of them male—although not all of them were discussed during her testimony. She testified as herself and said she could not remember the incident. She also testified as Jennifer, who said she was 20 years old and went on a coffee date with Peterson. Jennifer said she had sex with Peterson in the front seat of his car.

The prosecution was believed to be the first in U.S. history in which a defendant was accused of raping a woman who did not remember the rape because the victim was one of her multiple personalities. The prosecution charged Peterson based on a Wisconsin statute that makes it a crime to have sexual intercourse with someone who is mentally ill if the accused knew of the victim’s condition and if the mental illness made the victim “incapable of appraising the person's conduct.”

A month later, in October 1990, the woman called the police to her home saying that one of her personalities was holding a knife to another and that she thought she would be killed. Police found the woman unharmed, sitting in a chair in her home. She was then hospitalized.

In the fall of 1990, Peterson, a grocery store worker who was married, went on trial in Winnebago County Circuit Court on a charge of second-degree sexual assault.

Winnebago County District Attorney Joseph Paulus told the jury in his opening statement that Peterson manipulated the victim into having sex. Paulus said Peterson “told the host personality to go away and asked for Jennifer to come out. The host personality had absolutely no idea what was going on.” Paulus said that Emily, another of the woman’s personalities, saw him having sex with Jennifer and that Peterson told Emily not tell anyone and “keep our little secret.”

A psychiatrist testified that he had been treating the woman for four years and had diagnosed multiple personality disorder. He testified that by the time of the trial, the number of the woman’s multiple personalities had increased from 21 to 46.

A neighbor to the woman testified that Peterson knew the woman had a split personality before he had sex with her. “We explained that some of these personalities were vulnerable,” the neighbor testified. “He (Peterson) said, ‘I see. I understand.’”

The woman displayed six different personalities during her testimony, including that of Jennifer. The complaining witness said that Jennifer didn’t know what sex was but when Peterson asked if he could “love” her, Jennifer said yes and they had sex in Peterson’s car in a municipal park.

The complaining witness said she learned about Jennifer having sex with Peterson from Emily (another personality), who was a six-year-old girl. The complainant said Emily “likes to peek” and that Emily saw Peterson and Jennifer having sex.

The prosecution also presented a statement signed by Peterson during his interrogation in June 1990 admitting that he knew the woman was mentally ill.

Peterson, however, testified that he did not learn that the woman was mentally ill until after he was charged with sexually assaulting her. He said he had no idea that she had multiple personalities when they went on their date, and that she consented to have sex with him. By the time he was interrogated, he said he had learned of the woman’s accusation and had been told she was mentally ill. He claimed that he signed the police statement because he was tired of being interrogated.

Peterson said he met the woman two days before the incident on a fishing outing and wrote down her telephone number after she agreed to go on a date. He testified that he asked the woman “if I could love her. She said, ‘Yes.’”

On November 8, 1990, the jury convicted Peterson of second-degree sexual assault. Jurors later said they were swayed by the statement that Peterson signed during his interrogation.

The case attracted worldwide attention, particularly in the tabloids. The prosecutor, Joseph Paulus, was accused of trying to negotiate a movie deal while the trial was going on, a charge he denied. A counselor who worked with the victim was fired amidst allegations that she persuaded the woman to sign a contract for the book and movie rights to her story. The counselor then revealed that the neighbor who had testified that Peterson knew of the woman’s multiple personalities was having a sexual relationship with the woman at the time and that it had been going on for a year. The counselor alleged that the prosecution knew about the relationship but never disclosed it to Peterson’s defense lawyers.

Paulus denied that he knew of the relationship. At a hearing, the neighbor admitted that he had a sexual relationship with the woman. The alleged victim also testified at the hearing and at first denied having such a relationship, but later admitted it was true. Those admissions meant that one of the prosecution’s witnesses had engaged in the very behavior that Peterson was accused of—having sex with the same mentally ill woman.

Based on these disclosures, Peterson’s lawyer filed a motion to vacate his conviction because the prosecution failed to disclose the relationship between the witness and the complainant. The motion also claimed that the judge had unfairly barred the defense from having their own psychiatrist examine the woman prior to the trial.

On December 18, 1990, Winnebago County Circuit Court Judge Robert Hawley granted the motion and vacated Peterson’s conviction. The following day, the prosecution dismissed the charge.

Paulus, who had been elected District Attorney in 1988, was defeated in 2002 after allegations that he had sex in his office. He was later convicted in federal court for taking almost $50,000 in bribes, between 1998 and 2000, in exchange for reducing or dismissing criminal and traffic cases for clients of attorney Milton Schierland. Paulus was sentenced to nearly five years in prison.

– Maurice Possley