When he did die there was nothing sinister about it. The elevator at Expo, the magazine Larsson founded, was broken. A chain smoker with a terrible diet, he climbed seven flights of stairs and collapsed at the top. He died of a massive heart attack at the hospital.
When the Millennium series, as it's known, became a success, Gabrielsson said at first the family supported her.
"You were his wife, it is not our inheritance -- it's yours," Gabrielsson said the family told her. "But something changed them. Something changed then, and I ended up in the position where all Swedish inhabitants are, with nothing."
The Larssons have argued the law is the law. They offered Gabrielsson about $2.6 million and a seat on their board. She flatly refused.
They live in a small university town in northern Sweden. There are no reports of glaring displays of their new wealth. They have made significant contributions to the organizations Stieg Larsson supported, but they declined our request for an interview.
Both sides have said hurtful things. On Swedish television in 2008, Joakim Larsson described Gabrielsson as unwell, perhaps unfit to manage Stieg Larsson's work.
Gabrielsson said she knows how Stieg would have felt.
"Extremely furious that his legacy is being handled like a sack of potatoes, chopped up into chips that are sellable, he would have been furious and he would have gone to a great extent to exact revenge," she said.
There is yet another twist in this tale: speculation -- practically a Swedish parlor game -- that Stieg Larsson did not write the books alone. Some say Gabrielsson was a key participant.
A colleague of Larsson's from the 1970s and 80s, Anders Hellberg, who now works for Sweden's major daily newspaper, Dagens Nhyeter, described Larsson's writing as childish.
"His writing was no good, syntax, sentences, spelling," Hellberg said. "In my view he couldn't have written it."
For others, the novels with Larsson's name on them came as no surprise.
"He was almost a nerd when it came to crime novels," said Daniel Phool, editor of Expo. "Stieg was a storyteller, he loved to tell stories and he told them very well."
But did he do it alone? Gabrielsson, a published writer in her own right, defends the man she loved but leaves the door open.
"I cannot see in the books what was originally Stieg's things and what was originally my things," she said. "Being together with someone for 30 years, large chunks of it become ours. ... He sort of held the pen, but just being able to be an efficient writer doesn't create any books. You have to be able, to have thoughts, the rest as well."
We asked Gabrielsson if she was part of those thoughts.
"Yes, that's how he saw it, yes," Gabrielsson said.
In another instance of life imitating art, Gabrielsson may have a final card to play.
In the book, a character suddenly dies. The protagonist discovers an unfinished -- and highly valuable -- book on his laptop.
In real life, reports have emerged that Larsson left at least part of a fourth book on his own laptop -- and whispers have circulated that Gabrielsson has it.
Millions of fans may hope so. Gabrielsson said she has not read a fourth book, but she knows what might happen. She will admit that she and Larsson talked about it and specifically what the future might hold for Lisbeth Salander in a fourth book. Could she write it?