Erupting in the kitchen of the modest north Minneapolis home, the fire that killed a retired bus driver spared a treasure worth more than $1 million.

Stacked high and deep in a spare bedroom that escaped the flames and water hoses last July, the thousands of comic books Gary Dahlberg had spent a lifetime collecting remained just as he had kept them, carefully cataloged and perfectly preserved.

"He loved his [comic] books," his sister, Wendy Kuiper, said. Her brother was 12 or 13 years old when he began plunking down 12 cents an issue for the comic books in the early 1960s. "As he got older, my mother would ask, 'What are you going to do with all those books?' My mother used to say they couldn't be worth anything."

What neither knew was that 2,500 to 3,000 of Dahlberg's 20,000 comic-book collection would end up "easily" worth more than $1 million. "Maybe closer to $2 million," said Ed Jaster, senior vice president of Heritage Auctions.

Three of the books already sold for a total of $80,000, including $47,800 for a 1963 copy of the first "Amazing Spiderman" issue. Heritage expects to auction about 450 books on May 5 in New York. The rest -- what Jaster said is "the best of a silver age collection we've ever handled" -- will be sold over the next year.

Dahlberg's 1963, No. 2 "Spiderman" issue is probably one of the "finest known examples" of five known copies, Jaster said. "This book could be worth well over $100,000."

That's more zeroes than Dahlberg's family had ever imagined.

"I think my mom is now looking down and saying, 'Sorry, I didn't know,'" said Kuiper, the oldest of Dahlberg's four sisters.

Dahlberg, who was 62 when he died, spent a lifetime collecting. He collected Star Trek plates, mugs and figurines, Peter Pan and Donald Duck collectibles and bins of Christmas ornaments. "He loved Christmas," Kuiper said. "It made him happy."

"He wasn't a hoarder," said Bev Johnson, his off-and-on girlfriend of 30 years. "He was visually stimulated and liked to have things to look at. ... He put toys in his fridge because he like to open it up and have something fun to look at."

But comic books were his passion. Many a trip and date included time spent in a comic book store or comic book show, Johnson said. She doesn't hesitate to confirm Kuiper's assessment that Dahlberg was more committed to his comic books than to the idea of marriage. "We had a lot of fun together," she said.

Art drew him in

It was the art of the comic book that drew Dahlberg in. He was 4 when his father died and likely was more withdrawn because of it, his sister said. "Drawing allowed him to go into his own world."

The stacks of comic books gave him access to the world of superheroes. He treasured them. "He would hold them and say, 'You can look at them, but you can't touch,'" Kuiper said.

After two years at Concordia University, he enrolled in art school in Minneapolis, Kuiper said. He earned a paycheck as a bus driver but his dream was to be a cartoonist. Breaking into the business wasn't easy, though, and her brother settled for driving city buses and collecting comic books.

He knew his collection was worth money, his sister said. But he only sold two comic books in his lifetime; one for $1,000 to buy a computer that allowed him to catalog his collection and another for $50,000 to pay off his house. Most of the collection -- about 17,500 books -- likely isn't worth much more than Dahlberg paid, said Jaster of Heritage Auctions. But more than 2,500 books are highly prized. If he had sold his collection, he likely could have retired comfortably 15 years ago rather than seven months before he died, Jaster said. "He knew they had a lot of value but he would rather live humbly than cash in these comic books."

The books' values are a credit in part to the fact that Dahlberg was a picky collector and Minnesota's climate. "What kills books is heat and light," he said. "He probably read them once and then put them away lovingly," Jaster said.

Since Dahlberg's death, the highly valuable books have been inspected, graded and confirmed as an original-owner collection known as the Gary Dahlberg Collection to honor the 30-plus year bus driver veteran and "ensure Gary's comic book immortality."

That gives his sister chills. "You think, oh, he never married. He never had kids. Oh, poor guy," she said. "But he loved these comic books."

Mary Lynn Smith • 612-673-4788