Forty years ago today, my life changed nearly as fast as you can say "Marjorie Congdon LeRoy Caldwell Hagen."

June 27, 1977. I was driving north on I-35 — a rookie features reporter for the Star Tribune in my first year out of college — off to interview strawberry farmers in Askov. En route, a radio report said Duluth police were investigating a double homicide, but gave no details.

Hmmm. Strawberries? Or murders? It was an easy choice for me, but would the bosses agree?

A freeway exit loomed and I called an editor who, bless her soul, said: "Go ahead and chase the Duluth story."

At the police station I learned the victims were heiress Elisabeth Congdon — 83 years old and partially paralyzed — and her night nurse, Velma Pietila. It was too late for the paper to send a "real reporter," but they assigned veteran journalists to work the phones while I handled on-the-scene reporting.

It was my big break, but who'd imagine the case would lead to a career-long reporting quest that's taken me to Denver and Latrobe, Pa., to Tucson and Ajo, Ariz. I covered two murder trials and testified at one. I spent much time, alone and uneasy, with the confessed murderer, Roger Caldwell. And I was soundly rebuked not long ago by the aforementioned Marjorie, Miss Congdon's adopted daughter, who was charged with planning the murders but was acquitted.

Early on, I faced dilemmas involving sources. Despite her grief and shock, the nurse who found the bodies gave me exclusive crime scene information and details about the reclusive Miss Congdon. I was elated with the front-page story until we learned that the nurse had once lost her license for taking drugs from a Duluth hospital. Editors insisted on a story about her transgressions, even though she'd given me this major scoop. With a heavy heart, I called her for a quote.

Years later, to my great relief, she said she didn't blame me for that story.

And 10 days after the murders, I overheard talk about a Colorado connection and got an off-the-record scoop from chief investigator Ernie Grams. He outlined the investigation of Marjorie and Roger — it was the first time we'd heard the allegations of murder for an $8 million inheritance. He asked me to hold the story until they solidified the case, and promised to call me first with news of an arrest.

I felt crushed when editors balked at my deal, noting that colleague Peg Meier had found a search warrant in Denver detailing the Caldwell connection. We wrote the story, despite my promise to the detective. Late that night, Grams called to say they'd arrested Caldwell. He kept his part of the bargain, even if I hadn't. I called the office and, for the first and only time, said: "Stop the presses!"

A headline reading "Son-in-law investigated in Congdon murders" was changed to "Son-in-law arrested in Congdon murders."

Sure, there've been times over 40 years when I wished the whole thing would end. It's a burden to keep "plugged in" with sources that long and worry about being beat on the story. But I've been driven by the heady sense of being the "expert" on the case.

That professional pride was heightened in the early 1980s when the University of Minnesota Duluth, now the mansion's owner, began offering tours but refused to tell visitors about the murders. Perplexed by their attitude, I wrote "Secrets of the Congdon Mansion" as a guide. For the first 20 years, the mansion gift shop refused to sell my book. Then they did sell it for almost 15 years, using proceeds to pay for repairs. Now it's banned again. Officials tell me they want to focus on the home's architecture and the family's legacy rather than the murders.

Scariest part of covering the story? Meeting Roger, at his request, behind an abandoned Pennsylvania train station soon after his controversial release from prison. He looked quite portly as he approached my car, and I thought: "I can outrun him."

On another trip, he met me at the small Latrobe, Pa., airport and offered to let me stay with him and drive his 15-year-old station wagon. I declined the housing offer, but we did use his old car to ramble around town and chat. He asked me to drive, but then warned that the brakes weren't very good. "Great," I thought. "So this is how he's going to get me."

My theory on the case: I'm sure Roger was involved in the murders, but after spending much time with him I don't believe he could have planned it himself. He was a mouse of a man, easily led, and, even if timid, seemed capable of such a heinous crime, especially when drinking. Which he did. A lot.

I suspect an accomplice was with him in the mansion that night. Maybe the other person killed the women. I pressed Roger on these details, but he never elaborated, fearful of being charged with perjury. He was perpetually broke, so I gave him my last $20 bill before leaving.

He lived the last five years of his life on welfare, without hope, and killed himself in 1988. I was one of only nine people at his funeral and I felt sorry for his family, and for him, because he'd come to such a pathetic end.

And Marjorie? After her acquittal she kept the story alive with a string of criminal acts: bigamy charges, two arson convictions, fraud and another charge, later dropped, that she killed her third husband.

Marjorie receives about $50,000 a year from the inheritance and lives in Tucson.

I often hear from folks who like bubbly Marjorie when they first meet her, but soon realize something isn't right. So they google her — and e-mail me to ask if it's all true.

Following a lead from her former friends, I found Marjorie two winters ago at a public dog park in Tucson. Her Doberman was inside the gate, thankfully, when I introduced myself in the parking lot.

"I know who you are," she said. "You've been stalking me for years."

I said I was just doing my job and hadn't seen her since a 2001 parole hearing (which went poorly for her).

"Get out of here now, or I'll call the police," she said.

I left.

But I'll keep trying because she's almost 85 and I'd hate for her to take those secrets to the grave.

Joe Kimball, author of "Secrets of the Congdon Mansion," was a Star Tribune reporter and columnist for 31 years. Since retiring in 2007, he's written for MinnPost and continued to follow the Congdon case. He just filed a report on the recent death of Elisabeth Congdon's other adopted daughter, Jennifer Johnson. And he served as a consultant for the History Theatre's 2015 production of "Glensheen: The Musical," re-opening July 6.