They found the abandoned Chevy Caprice station wagon out past the Staples cemetery and the old Warner bridge, past the meandering Crow Wing River where the local kids go to swim on hot summer days.

It was at the end of an old logging road, surrounded by thickets of hazel and acres of swampland, the wheels partly buried in mud.

This is where Peter Achermann vanished, the day before he was to speak at his granddaughter's wedding, four long years ago.

Because they had been married more than 50 years, Delaine Achermann knows what her husband would have done if he'd gotten stuck in the mud.

"He would have spun the tires and there would be mud everywhere," Delaine said. "He would have gotten out of the car, lit a cigar. I just know what he does."

But there was no mud, no cigar stubs and no sign of Peter.

The day he disappeared, authorities began searching the area around Staples for Achermann. More than a hundred people joined the search. They used cadaver dogs, and the National Guard even got involved. They have also scanned the shallow Crow Wing River several times, and combed the swamp.

Nothing.

Cass County Chief Deputy Erick Hoglund said the case is still open, and that authorities are "considering all options." Hoglund said they have followed several leads over the past few years, but so far none have panned out. They are offering a $20,000 reward for information if there was foul play.

The last image of Achermann is a grainy video of him getting into his baby blue car outside Ernie's Food Market in Staples, where he had stopped to get groceries. He had also been at the Lakeland hospital to pick up prescriptions for Delaine. He was a well-known figure in the area, with his long gray beard and ever-present beret.

Because of the pending wedding, Achermann would have headed home. There's "no way" he would have driven down that logging road in the early afternoon of July 25, Delaine said.

Although he was 82, Achermann was in good health and did not suffer from any type of dementia.

"He was sharp. He paid the bills and was fairly capable," said Delaine.

Peter moved to Minnesota from Switzerland when he was in his 20s and settled near Osakis. Delaine lived on an adjacent farm. They fell in love, married and eventually bought 600 acres of land north of Leader. They raised cows and kids and fostered 17 children over the years. Even in his 80s, Peter volunteered to help senior citizens. He was the type of guy "to give you the money out of his pocket," said Delaine.

Ruth Boldan was one of the first to meet the Achermanns when they moved to the area.

"He was a very good man," said Boldan. "Nobody I knew would say a bad word about him. When he first came here, Peter had a thick Swiss accent. He was very thoughtful and he didn't gossip or point fingers. I could listen to him all day."

Though authorities won't say if they think Achermann was kidnapped or harmed, friends and family say it's the only thing that makes sense.

"The sheriff said they usually find older people within one hundred yards of where they were last seen," said Peter's son, Franz. "There are a million theories out there, but I think it was some predator preying on the weak."

Achermann was certainly the type of person to pick up a hitchhiker or offer someone a ride, his family said. He was not depressed, and was excited to speak at his granddaughter's wedding the next day.

"It's my opinion, but I think it had to be a local, someone who knows these back roads," said Delaine. "It's just so puzzling why someone would want to harm an older man."

Achermann had written his autobiography in his native language, and after his disappearance a niece translated it into English. The book is available in stores in the area, but it still lacks an ending.

The Achermann family marked the fourth anniversary quietly Friday. They admit they don't think there is a good chance Peter is still alive. Because Peter is still considered a missing person, his family has not been able to collect a small life insurance policy.

"We each deal with it our own way," said Franz. "We just wish it could be settled. Each Memorial Day we wonder, where do we bring the flowers?"

jtevlin@startribune.com 612-673-1702