The 58-year-old comic book was part of a collection at a museum in Köinge, in southern Sweden, run by the couple.
When they split up, they both claimed to be the rightful owner of the comic book. But in 2004, one of the couple decided to shut down the museum and sold the comic book to a third party, regional daily Hallandsposten reported in its online edition.
As a result, the other spouse reported the comic as stolen to police, and it was confiscated pending a ruling.
If in mint condition, the item would be considered a rarity by collectors and could be worth up to 125,000 kronor (16,200 dollars), according to Swedish news agency TT.
Prosecutor Sonja Seligmann said she would soon rule on the matter.
In the meantime, the comic book remains under lock and key with the Halland police.