There is no video surveillance footage of the violent Thanksgiving Day showdown between Gabriel Aubry and Halle Berry's fiance Olivier Martinez -- and it's all because of Halle's old stalker.
Law enforcement sources tell TMZ, when detectives visited Halle's home last year to investigate a scary stalker situation, they advised her to re-position her home security cameras to face the fences surrounding the property ... in order to catch a possible intruder.
Halle obliged ... and the cameras have remained facing the fences ever since ... and could not have captured the front door area of the home where the fight between Halle's past and present men took place.
Law enforcement sources tell TMZ, detectives have reviewed the available footage -- shot at the time of last week's brawl -- and confirmed the fight went down outside of the cameras' field of vision.
As for Gabriel's claim that Halle could have erased the video -- we're told cops DO NOT believe the security footage was altered in way ... it just plain missed the shot.