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On a rainy June night 45 years ago, retired church secretary Milda McQuillan left her northern Minnesota lake cabin in a pea-green 1968 Dodge and headed out to visit friends 18 miles away on Bad Medicine Lake near Park Rapids.

Her car stalled in the swampy, lake-dotted and densely wooded terrain. A postal carrier helped her get the car restarted. Somehow on the wrong road, she got directions from a truck driver only a mile from her destination. He told her to take a left at the Y down the road.

He was the last known person to see Millie, as everyone called McQuillan. After her sister reported her missing, searchers combed the woods hand in hand, eventually finding her car, rain hat and coat belt — but no body. She was 71, a longtime widow and mother of two.

No one has ever been arrested in what is still an open case. Her daughter and son assume she was murdered.

"I'm sure and I just hope it was fast and she didn't suffer," Carol Hinze, 81, said from her home in Little Falls. "It's hard not to be able to put it to rest. I still cry over it; I didn't get to say goodbye."

Hinze was 36 with three kids of her own when her mother disappeared. Her brother, Dennis McQuillan, was 27. They declined to hold a memorial service, hoping grouse or deer hunters might find Millie's remains.

"Would we like to know what happened? Probably. Would it change anything? Probably not," Dennis said from his home in Florida. He's now 72, one year older than his mother was when she went missing.

The youngest of 10, Milda Dahl was born in 1903 in Roseau County in far northwestern Minnesota. She married dentist Herbert McQuillan on June 18, 1928, almost 47 years to the day before she would disappear.

They lived in St. Paul from 1929 until after Herbert's World War II service, when he became the chief dental officer at the Veterans Hospital in Fargo. Millie was an avid poker and cribbage player and a fine cook, her children said.

"My mom's recipe boxes were full of complete meals because our dad didn't want to have the same dinner twice in the same month," Hinze said.

Herbert died in 1951 at age 47 when Carol was 12 and Denny was 4. They'd just purchased property on Round Lake near the village of Ponsford, about 30 miles northeast of Detroit Lakes and 200 miles northwest of the Twin Cities. The kids remained close to their mother, and they credit her scrappiness for being able to keep the Round Lake cabin.

When Millie retired from her office job at what is now Macalester Plymouth United Church in the mid-1960s, her kids surprised her with a plane ticket — her first — to visit friends in Texas. She moved from St. Paul to the cabin in 1966, living with her older sister, Ida Dahl.

Ida was the one who reported that Millie was missing on June 17, 1975, after she called the couple her sister had been going to see on Bad Medicine Lake, a deep body of water some Ojibwe believed held bad omens because it has neither inlet nor outlet. The couple told Ida that Millie had never arrived.

Carol said many suspicious details soon emerged. The man and woman from Bad Medicine Lake whom Millie planned to visit didn't join the volunteer searchers who looked for her, including farmers, White Earth tribal members, Boy Scout leaders and others. A police officer interviewed the man three days after Millie disappeared and noted that his pants were wet; he said he had been just walking down the road, but the wet clothes suggested he had been in tall grass deep in the woods.

Gov. Wendell Anderson initially refused to send in National Guard troops "because my mother wasn't worthy enough," Hinze said. But U.S. Sen. Hubert Humphrey sent 52 guardsmen to help scour the woods.

"And my mother hated Hubert Humphrey," Hinze said. "She was a Republican all the way."

Becker County authorities flew over the area when Millie disappeared and saw nothing. But the Dodge turned up on a muddy, unused logging road a couple of days later. The belt and rain hat were found on a bush.

Hinze is convinced her mother's murderer first hid the car and then later planted it and the clothing on the logging road. "The car wasn't there when we first searched the woods," she said.

Last year, cadaver dogs searched the area for remains. Nothing was found.

"I could never again stay at the lake house, it was too hard," Hinze said. They couldn't afford to keep the place and sold it years ago.

"I feel blessed by the 27 years I had with my mother," Dennis said. "She's still with me and I try not to dwell on the negatives, and [instead] think about her life and all those volunteers who came out to help us search the woods."

In the meantime, they've been to psychics and a White Earth medicine man in hopes of solving the mystery.

"Whatever happened, we think it happened fast," Dennis said. No checks or credit cards were ever used, he said, "so no one had any reason to hold her."

Curt Brown's tales about Minnesota's history appear each Sunday. Readers can send him ideas and suggestions at mnhistory@startribune.com. His latest book looks at 1918 Minnesota, when flu, war and fires converged: http://strib.mn/MN1918.

Correction: Previous version of this article misstated in a caption the year when Milda McQuillan disappeared. It was 1975.