A number of stories have circulated over the years regarding the Paris crash, perhaps the most believable being that the TU144 was being shadowed by an aircraft that got too close, the TU144 needed to take avoiding action resulting in a journalistic type that they had in the cockpit falling on to the controls and the rest is history.
Another story was that they did copy designs of Concorde that they sourced however deliberately flawed plans were provided which resulted in the TU144 being the piece of cr@p that it was.