Raised in Washington D.C., she attended the National Cathedral School, followed by the University of Pennsylvania. After graduating with a BA in History, she enrolled in New York University's Graduate Program in Film and Television, earning an MFA in 1972. She worked in television news as an assistant film editor for NBC in New York, N.Y., then relocated to DC where she joined N-PACT, the Public Broadcasting Service's public affairs unit that first paired Robert MacNeil with Jim Lehrer. Among other programs, she worked on the rebroadcast of the Watergate hearings in 1973. Hellmann also spent time at TVN, the news syndication service underwritten by Joseph Coors, and NBC in Washington, DC. In 1978 she joined Burson-Marsteller's Chicago creative department where she worked until 1985. She founded Fischer Hellmann Communications in 1985, which specializes in video production, speech writing, and spokesperson training.
Hellmann's first crime fiction novel, An Eye For Murder, was published in hardcover in 2002 by Poisoned Pen Press and in paperback by Berkley Books. It was nominated for an Anthony for Best First, and won the Best First Readers Choice Award at Chicago's Love is Murder conference. Its protagonist, video producer and single mother Ellie Foreman, was featured in three additional novels. In 2007 Hellmann edited Chicago Blues, a short story anthology featuring over 20 prominent Chicago crime fiction authors including Stuart Kaminsky, Sara Paretsky, Barbara D'Amato, Sean Chercover, Marcus Sakey, Joe Konrath, Max Allan Collins, and others.
Her second crime fiction series, featuring Private Investigator Georgia Davis, debuted in 2008 with Easy Innocence. Its sequel, Doubleback (October, 2009, Bleak House Books), features both Davis and Foreman as co-protagonists.
Hellmann has published over 12 short stories and has been nominated for several major mystery awards, including the Anthony (twice) and the Agatha (once). She has won the Readers Choice/Lovey Award four times.
In 2006 Hellmann founded The Outfit Collective, a blog shared by seven Chicago crime fiction authors.