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Didi Cassidy is the attorney for the prosecution in the trial of former President Gaius Baltar.
Two weeks before the trial, Cassidy stays aboard Galactica, presumably for reasons of her personal security.
Defense attorney Romo Lampkin, acting on one of his kleptomaniac urges, steals one of her sandals from her room while visiting her. By the wear of the sole of said sandal, Lampkin (and later Lee Adama) are able to tell that she drags her feet as she walks (The Son Also Rises)
Cassidy's main indictment against Baltar is a comparison of the number of humans who settled on New Caprica and the ones who escape from the planet, despite the fact that Laura Roslin wanted Baltar charged with genocide due to Roslin's visions of Baltar on Caprica with Caprica Six. However, as there was no evidence for this, Cassidy goes after what Baltar did on New Caprica: as part of her case, she calls up Saul Tigh, Laura Roslin (Crossroads, Part I) and Felix Gaeta. After Gaeta's perjury on the stand, Lampkin's places Lee Adama on the stand, which she vociferously objects to, referring to him as "defense council" throughout his time on the stand. Despite the fact that she fails to obtain a guilty plea, Roslin congratulates her for her work (Crossroads, Part II).