The mystery surrounding the death of Floyd Mayweather's ex, Josie Harris, continues -- with no evidence of drugs or suicide at the scene, law enforcement sources tell us.
We broke the story ... Harris -- who has 3 kids with Floyd -- was found in her car in front of her family home Tuesday evening in Valencia, CA.
We're told one of her kids noticed Josie was unresponsive in the vehicle and made the call to 911. Lifesaving measures were taken -- including an attempt at CPR -- but it was too late.