CHICAGO — Recluse janitor Henry Darger spent more than 40 years in a tiny one-room apartment in Lincoln Park, writing, painting, sketching, collecting and fantasizing.

It wasn’t until after his death in 1973 that his works, discovered by his landlords, trickled onto Chicago’s art scene, with his fanciful stories and sometimes-violent imagery eventually gaining worldwide appreciation — and skyrocketing value.

Now, nearly a half a century later, a brewing legal battle over the rights to Darger’s legacy has landed in Chicago’s federal court, where a lawsuit was filed by his estate accusing the landlords of copyright infringement.

The lawsuit filed in U.S. District Court on July 27 names Kiyoko Lerner and the estate of her husband, Nathan, who together rented the third-floor room of their walk-up on West Webster Avenue to Darger beginning in the 1930s.

According to the suit, the Lerners have been illegally profiting from Darger’s works for nearly five decades, including his massive 15,000-page illustrated manuscript “In the Realms of the Unreal,” despite having no claim as heirs. Nathan Lerner, a photographer and industrial designer who first promoted Darger’s work, died in 1997.

The lawsuit comes six months after several of Darger’s purported relatives, all first cousins several times removed, filed an action in Cook County Probate Court seeking to be declared heirs to his estate. That suit is still pending.

The Lerners have long maintained that Darger was clear before his death that he didn’t care what happened to his work. An attorney who represents Kiyoko Lerner in the probate matter did not return calls seeking comment.

By now, the story of Darger’s unlikely rise to world acclaim is well known. After he was born in Chicago in 1892, his mother died when he was 4. His father, a tailor, struggled with health issues. After Darger had behavioral problems at school, he was sent to what was then known as the Illinois Asylum for Feeble-Minded Children in downstate Lincoln.

Darger would later incorporate many of his experiences at the asylum, including children being subjected to forced child labor and severe punishment, into his art. After his father died in 1908, Darger escaped from the facility and walked 160 miles back to Chicago, where he found work as a custodian at a Catholic hospital. Aside from a brief stint in the military during World War I, it would remain his profession for the next 50 years.

In 1930, Darger began renting a large, third-floor room in a brick home at 851 W. Webster Ave. He’d been living there for nearly 30 years when Nathan Lerner bought the building in the late 1950s. Kiyoko Lerner and others who had contact with Darger in his later years remembered him as quiet and idiosyncratic, detached from reality in many ways but not dangerous.

He was obsessed with the weather and was a voracious reader of newspapers and magazines, according to the documentary. He wore the same threadbare army coat and could often be seen prowling alleys near the apartment, looking for collectibles in the trash. At night, when he’d return home from work, neighbors would hear voices coming from his room, like a large group of people having a boisterous discussion. It was Darger, immersed in his world, talking to himself.

In the mid-1960s, after he was forced to leave his job due to declining health, Darger was spending virtually his entire life in the room. There, he continued working on his life’s opus, the fantasy story of the Vivian Girls, seven Christian princesses who join a bloody rebellion against child enslavers. The work, which ultimately filled some 15,145 typed pages, is illustrated with hundreds of painted scenes, drawings and stencils.

By early 1973, Darger was too sick to live alone and was moved to St. Augustine’s Home for the Aged, the same institution where his father had died. When the Lerners and some neighbors went into his room to begin clearing out his things, they couldn’t believe their eyes.

“I distinctly remember going up that narrow staircase and entering a totally new world,” Lynne Warren, then a neighbor and art student, told the Tribune in 2000. “I really felt like I had stepped inside Henry’s mind.”

Resting on an iron bed were the volumes making up “In the Realms of the Unreal.” Also found were Darger’s detailed memoirs, a meticulously kept weather journal, and decades-old newspaper clippings of disasters and missing or slain children tacked to the wall.

“We were stunned,” Kiyoko Lerner told the Tribune. “We didn’t know what to make of it.”

David Berglund, a tenant in the building, said he remembered visiting Darger in the hospital before he died and praising his old neighbor’s work.

“He looked at me like I’d sucker-punched him,” Berglund remembered. “He looked at me and said, ‘It’s too late now. It belongs to Mr. Lerner.’”

Darger died on April 13, 1973. He’s buried at All Saints Cemetery in Des Plaines, where his headstone is inscribed with the words, “Protector of Children.”

Nathan Lerner saw the potential in Darger’s work and used his connections in Chicago’s art world to try to drum up interest. They preserved Darger’s room and invited artists and students to dive into the dense and mysterious creations.

Four years after Darger’s death, his work was first featured in a show at the Hyde Park Art Center, but international acclaim wouldn’t come until the 1990s with a show at the American Folk Art Museum in New York. Since then, Darger has been recognized as one of the world’s premier “outsider” artists, and his work has inspired poems, an opera, even a rock band called the Vivian Girls.

With the notoriety, of course, came the inevitable dollar signs, and Darger’s works, particularly the illustrations, began fetching hundreds of thousands of dollars in art house auctions.

The value continues today. According to the lawsuit, Christie’s auction house estimated the sale price for one page from “In the Realms of the Unreal” to be between $200,000 to $400,000. The painting wound up selling for $675,000.

The lawsuit alleged that over the years, the Lerners “have generated tens of hundreds of millions of dollars from the unauthorized exploitation of the Darger works.”

But even if the Lerners are found to have violated the law, how much could be recouped for Darger’s estate — and who would share the proceeds — is still a very murky picture. In Cook County Probate Court, Judge Kent Delgado has granted the petitioners an extension to prove up their claim as Darger’s rightful heirs, which can be a lengthy process.

Meanwhile, many of the contents of Darger’s old room on West Webster Avenue, which had been preserved by the Lerners, are now on display at Intuit: The Center for Intuitive and Outsider Art on Chicago’s Near West Side.

But the room itself is long gone. Back in 2000, Kiyoko Lerner’s stepson, Michael, told the Tribune he was gut rehabbing the building, with Darger’s room serving as the master suite.

The building sold in 2006 for $2 million, records show.