"working pro bono"

The Law Never mind Mrs Sherlock, the tenacious Mrs. Grace Humiston who helped to convict the murderer of a high school girl has something of the Sarah Lund about her:

"Humiston spent 15 hours a day on the case, working pro bono, interviewing Harlem residents who might have noticed suspicious activity around Cocchi’s shop. One man recalled seeing Cocchi emerge from his basement around midnight on February 13, covered with dirt and appearing “nervous.” Another spotted Cocchi the following night, again “dirty and nervous.” On this evidence, Humiston went to Cocchi’s shop, determined to get into the cellar."

Indeed this historic case demonstrates that for all the obfuscation, Forbrydelsen's story is disappointingly realistic.