NEW YORK (NYT NEWS SERVICE).- Lynn Shelton, the acclaimed director of “Humpday,” “Sword of Trust” and numerous other films, died Friday at Keck Medical Center in Los Angeles. She was 54.

She suffered from a previously unidentified blood disorder, said a spokesman, Adam Kersh.

Shelton was best known for her work as a writer and director of independent films, intimate seriocomic dramas focused on relationships and family, often with complicated women at their centers. She worked in a shaggy, freewheeling style, encouraging actors to improvise and contribute, drawing freely from their own experiences to craft their characters and tell her stories.

Lynn Shelton was born on Aug. 27, 1965, in Oberlin, Ohio, and grew up in Seattle, the daughter of Wendy Roedell, a developmental psychologist specializing in early childhood education, and David “Mac” Shelton, a trial lawyer and mediator-arbitrator. They divorced in 1974. Like her parents, Shelton attended Oberlin College before returning to the Pacific Northwest to attend the University of Washington School of Drama. She then moved to New York, studying photography and related media at the School of Visual Arts in Manhattan.

She was already interested in filmmaking, she told The New York Times in 2009, but “I just did not have the confidence to do it.” In 2003, she attended a Q&A with the French filmmaker Claire Denis, and found herself inspired not only by Denis’ talent, but also by her tenacity. “I thought: ‘Oh, my God. She was 40 when she made her first film. I thought it was too late for me, so in my head was, ‘Oh, I still have three more years.’”

Shelton felt she “had to find a backdoor way in. I couldn’t even go to film school, I had to start making my little movies and learning about editing.” A number of like-minded filmmakers, including such future collaborators as Greta Gerwig, the Duplass brothers and Joe Swanberg, were doing the same thing, crafting microbudget, dialogue-driven, semi-improvised features on digital video. Shelton directed her first, “We Go Way Back,” in 2006; its follow-up, “My Effortless Brilliance,” won her the Someone to Watch Award at the 2009 Film Independent Spirit Awards.

But it was “Humpday” that put her on the indie map: it won a Special Jury Prize at the 2009 Sundance Film Festival, was screened as part of the Directors Fortnight program at Cannes and won the John Cassavetes Award (for films costing less than $500,000) at the 2010 Indie Spirits. The Times’ Stephen Holden wrote, “The movie’s unblinking observation of a friendship put to the test is amused, queasy making, kindhearted and unfailingly truthful.”

Holden also called it “a Judd Apatow or Kevin Smith buddy film turned inside out,” but Shelton resisted the temptation to parlay its success into a career in the Hollywood mainstream. Instead, she maintained a home base in Seattle and kept her stories (and budgets) modest, continuing to focus on the interpersonal dynamics of richly drawn characters in subsequent works like “Your Sister’s Sister,” “Laggies” and “Sword of Trust.” That movie, Glenn Kenny wrote in The Times, “is more concerned with its people — marginal folks — and their dreams and disappointments, their fervent belief that with just a bit more dough in their pockets, they could get ahead enough to relax a little. The humor has a persistent goofy streak, but what sticks to the ribs is the poignant stuff.”

Shelton subsidized her small-scale film efforts with copious work as a director-for-hire in television, overseeing episodes of “Fresh Off the Boat,” “Mad Men” and “Little Fires Everywhere,” among others.

Shelton is survived by her son, Milo Seal; her ex-husband, Kevin Seal; and her parents, Wendy and Alan Roedell and David “Mac” Shelton and Frauke Rynd. She is also survived by her brothers, David Shelton and Robert Rynd, and sister, Tanya Rynd, as well as the comedian and podcaster Marc Maron, with whom she spent the last year of her life.

Shelton met Maron while directing episodes of his series “Maron” and “G.L.O.W.”; she also directed his two most recent stand-up specials, and she cast him in “Sword of Trust.” In a May 7 interview, Shelton and Maron revealed they were collaborating on a screenplay while sheltering-in-place.

“She was a beautiful, kind, loving, charismatic artist,” Maron said in a statement. “Her spirit was pure joy. She made me happy. I made her happy. We were happy. I made her laugh all the time. We laughed a lot. We were starting a life together. I really can’t believe what is happening.”

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