The state’s highest court Thursday upheld a Multnomah County judge’s suppression of an alleged confession made by accused serial killer Homer Lee Jackson III, marking a significant setback to a Portland case that has been pending since his high-profile arrest three years ago.

Police arrested Jackson, now 58, in October 2015 and accused him of strangling two teenagers and two women in their 20s who worked as prostitutes in the 1980s. He’s pleaded not guilty to aggravated murder charges.

The court found that the two veteran Portland police “detectives’ methods and inducements may have persuaded defendant to tell the detectives what they wanted to hear, whether or not that was the truth.’’

The state Supreme Court upheld the ruling in 2017 by Multnomah County Circuit Judge Michael A. Greenlick, who threw out statements Jackson made during more than seven hours of questioning over two days by two Portland cold case detectives when he was taken into custody. Greenlick found they were “made under the influence of fear produced by threats (and promises of leniency).’’

The state’s high court said it considered the totality of circumstances, including Jackson’s diagnosed schizophrenia, his significant problems with memory, that he wasn’t allowed to call his family until Det. James Lawrence told Jackson that he felt "we are working together on this,’’ and that Jackson had provided incorrect details about some of the killings.

The state Supreme Court wasn’t as concerned by the detectives’ suggestions that Jackson could ease the suffering of the victims' families or clear his conscience by giving them information on the homicides of Essie Jackson, 23, killed in March 1983; Tonja Harry, 19, killed in July 1983; Angela Anderson, 14, killed in September 1983; and Latanga Watts, 29, killed in March 1987. Homer Jackson and Essie Jackson aren’t related.

Each of the victims was African American, died of asphyxiation by strangulation or a ligature, was sexually assaulted and walked the old Union Avenue, now Martin Luther King Jr. Boulevard, as prostitutes, police said.

What the court found disturbing was: the detectives’ suggestion that if Jackson didn’t confess, he might be tied to additional murders or crimes, that he’d face an unforgiving jury that would consider him a “monster,'' and the police would work to ensure he faced the harshest sentence.

“Defendant was told that it would be best for him to confess so that the detectives might eliminate him as a suspect in additional crimes and because it would give him more control over how the case would proceed in the future; that the jury would think poorly of him if he did not confess; and that if he did not confess, the detectives would do their best to ensure that he received the maximum possible sentence,’’ the Supreme Court noted.

Essie Jackson, 23, killed in March 1983; Tonja Harry, 19, killed in July 1983; Angela Anderson, 14, killed in September 1983; and Latanga Watts, 29, killed in March 1987. Each of the victims died of asphyxiation by strangulation or a ligature, was sexually assaulted and walked the old Union Avenue, now Martin Luther King Jr. Boulevard, as prostitutes, police said.

The court also highlighted Det. Lawrences’ likening of the case to a train during his interrogation, in which he urged Jackson to confess and "get on'' the train and then warned that if Jackson didn’t, he’d get "run over'' by the train. It also noted Detective Meredith Hopper’s suggestion that the detectives and a jury would view Jackson as a “monster,’’ if he didn’t come clean.

The high court was not convinced that Jackson’s statements to detectives on Oct. 15, 2015, were voluntary. It also upheld the circuit court’s suppression of statements Jackson made during a phone call to his sister on the second day of his questioning, noting that the detectives were present during the call and even participated in the call.

Homer Jackson was arrested in October 2015 and remains in custody, accused of aggravated murder in connection with four homicides from the 1980s.

Multnomah County prosecutors are reviewing the opinion “to assess any potential implications,’’ said Brent Weisberg, spokesman for the office.

Marc D. Brown, who argued the case as chief deputy defender for the Office of Public Defense Services, said the Supreme Court not only considered the coercive techniques that police used during their questioning, but also "the person upon whom the techniques are employed.''

"Although certain coercive techniques used on a particularly sophisticated suspect may not, under the totality of the circumstances, lead to statements that are involuntary, the same techniques used upon a person with mental health issues or intellectual disabilities, or a juvenile will likely lead to statements that are involuntary,'' Brown said. "Unfortunately, the police are still permitted to employ coercive techniques including lying to suspects during interrogation in order to get a confession but overall today’s decision is an important one to protect the rights of individuals suspected of a crime.''

Dean Smith, one of Jackson’s defense lawyers, said other defense motions, which have been on hold, are set for argument in May. Smith credited Jackson’s initial defense lawyer, Conor Huseby, now an assistant federal public defender, for challenging the confession. Huseby had argued that the promises of leniency mixed with threats showed the detectives were trying to manipulate Jackson into confessing to murders "it was abundantly clear he had no memory of.''

Prosecutors allege Jackson’s DNA was found at three of the crime scenes. Jackson’s lawyers have countered that his DNA isn’t the only male DNA at the scenes and often was found in less incriminating places than the DNA of other potential suspects.

-- Maxine Bernstein

Email at mbernstein@oregonian.com

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