In the days before Dorothy Fielding disappeared in the summer of 1967, a secret admirer kept leaving bouquets of handpicked flowers inside her car: marigolds, zinnias, red and pink roses, all wrapped in aluminum foil and accompanied with handwritten notes, one saying he was in love with her.

The 31-year-old had told her friends it was starting to creep her out. She was married, but as her friends would later tell police, she was having an affair. Her husband seemed to be catching on. She often returned home from work at Rosauers Supermarket in Spokane, Wash., hours later than expected, causing arguments.

But on the night of Aug. 18, 1967, Fielding didn’t return home at all.

Her car was discovered several days later in a grocery store parking lot, with cigarettes in the console rather than flowers, although she did not smoke. Her body was discovered eight months later, with a pile of dirt covering her badly decomposed corpse. She was wearing her Rosauers uniform, with her name tag still pinned to it.

Immediately, Spokane County sheriff’s investigators suspected the man who left the flowers. They wanted to know more about Fielding’s lover and were surprised to learn his identity: Duke Pierson, the security guard at Rosauers — and a former Spokane County sheriff’s deputy.

His life had seemed to be spiraling over the last year. Described as “mentally unstable” by other deputies, Pierson had abruptly resigned from the sheriff’s office in 1966 after he stopped coming to work and threatened to kill colleagues who questioned him. The sheriff’s office knew his wife, Sandra, had died of an apparent suicide in September 1967 while she was 20 weeks pregnant, less than a month after Fielding’s disappearance. But this was the first they were hearing of his affair with Fielding. They called him in for an interview where he admitted to the affair, but ultimately they let him go.

More than 50 years later, however, the Spokane County Sheriff’s Office is wishing they hadn’t.

On Monday, the sheriff’s office announced that it had filed an arrest warrant for Pierson on charges of first-degree murder in Fielding’s death, and also noted he is under investigation in the deaths of two other women that summer — his wife and another woman named Ruby Lampson. But just as deputies prepared to have him arrested, they discovered they had missed their chance: On Jan. 22, the 85-year-old Pierson died at his home in Andalusia, Ala.

It was three days before the sheriff’s office filed the warrant.

Now, armed with largely circumstantial evidence, investigators are seeking to unravel the three cases without the one man they believe ties them all together. Pierson’s two children, his second wife, his cousin, his former co-workers and others all believe he is responsible for one or multiple deaths, according to the affidavit. But the challenge for police is that, at least for now, there is no convincing DNA evidence to bolster the case, no fingerprints found at the scenes — only the decades-old memories of those who remember the events from the summer of 1967.

In his last interview with police before he died, Pierson claimed that he didn’t remember much.

“I will tell you this,” he told Detective Kirk Keyser in April 2018, according to the police affidavit. “I am sure if I had killed somebody I would remember. If everything else had failed out of my memory, that would probably still be there. But I have never killed anyone."

The sheriff’s office declined to make detectives available to answer questions about the case, but a 23-page affidavit filed in support of probable cause for Pierson’s arrest, obtained by The Washington Post, spells out their evidence.

The sheriff’s office reopened its investigation into Pierson last April after a call from someone inquiring about the Fielding case, the sheriff’s office said in a statement Monday. The caller remembered that Fielding was on the bowling team at the old Falls View Tavern, a riverside joint known to have a “scurrilous reputation,” as the Spokesman-Review’s archives described it, and located about 12 blocks from Pierson’s apartment during that time. That tip is how Keyser first made the connection, he said: Lampson, who disappeared the night of June 6, 1967, was a regular at the same tavern. In fact, she lived above it — and Keyser learned last year that she and Fielding knew each other.

Keyser was startled by the similarities to the Fielding case. Both women disappeared within two months of each other. Both of their haphazard shallow graves were discovered less than two miles apart, along the same dirt trails near the 7-Mile Off Road Vehicle Park. Both were clothed.

Keyser believed the same perpetrator had to be responsible.

Interviews with those close to Pierson all heaped suspicion on the ex-cop. Even his wife, Sandra’s, death, ruled as a suicide then, began to appear suspicious.

In the late 1960s, police heard one motive Pierson could have had for killing Fielding in an interview with his cousin, Bob. According to his cousin, just weeks before Fielding vanished, Pierson told Bob he was “in a bind.” Pierson said he and Sandra had just repaired their crumbling marriage during a trip to Hawaii — but upon his return, he discovered his girlfriend from Rosauers was pregnant. Pierson said he rushed to the doctor’s office, Bob recalled; Pierson had had a vasectomy years earlier and didn’t think he was capable of impregnating a woman, but apparently, Pierson told his cousin, something went wrong.

After reopening the case last year, Keyser tracked down Bob’s son, who was still living. He told the detective his father never stopped believing Pierson had killed Fielding and was involved in Sandra’s death because of that conversation.

Next, Keyser found Pierson’s two children, and they, too, were suspicious of their father.

They were teenagers when their mother, Sandra, was found dead in the back seat of her car inside an exhaust-filled garage on Sept. 12, 1967. A hose, fastened to the exhaust pipe with tinfoil, dangled inside the car’s rear window. Puzzling investigators, the engine was not running.

Neither of Pierson’s children believed their mother was capable of killing herself, or even of opening and closing the garage door on her own — but they knew their father was capable of making her do things she would not ordinarily do. He liked to practice hypnosis on her, both children remembered. Sheriff’s deputies who knew Pierson corroborated that story, according to the affidavit. Pierson’s son showed Keyser a letter he had always kept, one his father sent Sandra from Hawaii, inviting her to join him and apologizing for a cryptic incident involving a hose.

“As far as the situation about the hose, I told you that the only reason I agreed to it was to let you see that you couldn’t do anything more than I could do to you," Pierson wrote.

After Sandra died, he paraded her autopsy report around in front of the neighbors, noting that she was 20 weeks pregnant and that it must have been another man’s baby, his daughter told Keyser, because of his vasectomy. His daughter said it appeared to be a way to “justify” the suicide to them, according to the affidavit.

Within two months of his wife’s alleged suicide, Pierson had moved on. He married a woman named Donna — who told Keyser, when he found her, that throughout the short-lived marriage she was in constant fear of her husband.

Everything had been fine when they were dating. He would leave her flowers, she told police, and meet her at prearranged locations so they could sneak off on dates. But soon he turned controlling, jealous and sexually violent, she said. She told Keyser he had warned her that if she ever left him he “would make sure she didn’t wake up.” Sometimes he mentioned the missing girl he used to work with at Rosauers, appearing to suggest that she might end up the same way. The hypnosis spooked her.

Donna wanted a divorce. Pierson responded by threatening to hurt her horses and tried to kidnap her little sister, according to the affidavit. She got a restraining order and he responded by leaving notes in her car, she told police. “I saw you ... ,” they would say.

The stories of Pierson’s threats and bizarre behavior are arranged like scattered puzzle pieces in the 23-page affidavit, appearing to fit in the same corner but not yet connected. The affidavit doesn’t indicate any potential motive in Lampson’s death, for example, though it also makes clear the case is still under investigation.

In April 2018, Keyser flew to Andalusia — a town of less than 10,000 people in southern Alabama — to interview Pierson once again, hoping for answers.

By then, it had been roughly five decades since Spokane deputies had first interviewed him. Since that time, Pierson had been divorced at least twice, had been sentenced to two years in federal prison for his role in a cocaine-smuggling operation out of Bolivia and Mexico, and had lived in the Philippines, where he claimed to have fended off burglars in a gun battle.

He was now 85, sick and ailing.

Keyser found more inconsistencies than answers.

“It appeared as though Duke Pierson was trying to convince Keyser that he could not recall details of the past," Keyser wrote. "However ... Pierson was able to give very specific details about dates, people, locations and events during the 1960s, 1970s and 1980s, but ... claimed not to remember issues that were only related to the investigation of the death of Ruby Lampson and Dorothy Fielding.”

Pierson denied ever being accused of fathering a child with a co-worker at Rosauers — as his cousin alleged he had said — but later contradicted himself, saying he had been told about fathering a child but couldn’t remember by which woman at Rosauers.

When Keyser asked him about his affair with Fielding, he denied ever knowing a woman by that name and denied ever being interviewed by police about her disappearance. He said he dated “thousands” of women in that time period.

But one thing also stood out. Keyser asked about the flowers in Fielding’s car, and Pierson said yes, he had loved giving women flowers back then.

“Without any doubt,” he said, "it was from me.”

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