I thought the hardest part of profiling a man charged with murder would be convincing him to talk. Defendants in such cases rarely take the stand, let alone speak publicly before trial. But Mbyayenge "Robbie" Mafuta, a young man who is accused of murdering his prison cellmate a year ago, was eager to tell me and my colleague Colin Flanders about his life in Burlington, where he developed a serious mental illness before his incarceration.