Vivian Maier's name began appearing in news reports around 2010, a year after her death and three years after John Maloof bought a box of her street photographs at auction. He was just looking for pictures of Chicago history, but he discovered a devoted artist who shot at least a roll of film every day—yet never showed her work to anyone. Why?

As the full weirdness of that central mystery unfurls in the gripping documentary Finding Vivian Maier, another enigma emerges: Maier herself, a gold mine of a character. She was, in short, a shady lady. Even the directors seem startled by what they find on the trail of the peripatetic nanny behind the Rolleiflex.

A small group of Maier's pictures visited the Photo Center Northwest last year. Those images now, after watching the movie, take on a more ominous cast. Surely art shouldn't be altered by a posthumously pieced-together biography? But now we know that she was an intrusive shooter, angering people. Some of the expressions we see on the faces must have been directed at Maier. And what to make of the fact that Maier took pictures of a little boy lying in the street just after he'd been struck by a car—while she was the nanny charged with this boy's care?

Other art questions arise, too. Maloof has a grudge against museums, which haven't immediately found a way to canonize his heroine (and chief income source?). But the images being printed now from negatives are ones Maier never saw or selected herself. What were the artist's intentions? How long has it taken to insert other artists into the canon when they were discovered after death, and what processes were involved? The movie doesn't tangle with any of those issues. Last year's Photo Center show was called Out of the Shadows, but the shadows keep piling on.