Sienky Lallemand was a professional con man who made a comfortable living out of crime, although on one occasion he slipped up when he tried to blackmail a married man whom he had entrapped in a homosexual liaison; his victim refused to shell out anything, and Lallemand ended up behind bars. Sometime later he zeroed in on a woman with whom he had a great deal more success; Lisa Toney was married to a janitor, but she had grown tired of a regular, decent but unexciting guy, and was bowled over when Lallemand literally walked into her life. She was already living apart from Mark Toney; with her cooperation, Lallemand stepped smoothly into the unsuspecting janitor's shoes racking up massive credit card bills all over the place using his name. Toney suspected his estranged wife was aiding the scam, but he had no proof.
Although a quintessential psychopath, Lallemand was also a total hedonist and narcissist who had never killed before, so why would he send his love rival the letter bomb which killed him? That was Lisa's idea - her ex was heavily insured, and she was the beneficiary.
Lallemand returned to the Caribbean from whence he had come, and started a long distance relationship with another woman who was deeper than she looked. If you hadn't guessed already, this can only end very badly for all concerned, but at least there was justice for Mark Toney. The documentary makers speak to his family including his elderly mother. When the law finally caught up with Lallemand he was offered a plea to avoid a capital murder charge. He did so, and took Lisa Toney down with him. Lallemand's later conquest (who had sticky fingers) and the bomb maker also ended up behind bars.