Bobbi Kristina -- Autopsy Shows No Evidence of Foul Play

There are no obvious signs someone tried to kill Bobbi Kristina ... this according to the preliminary autopsy results.

According to the Fulton County Medical Examiner, the autopsy shows "no obvious underlying cause of death." The Medical Examiner goes on to say, "no significant injuries were noted."

Short story ... this could help Nick Gordon, who has been under the police microscope from the get-go.

The report says there were no previously unknown medical conditions that could have rendered Bobbi Kristina unconscious in the bathtub.

But the Medical Examiner says he has subpoenaed medical records, presumably from the hospital, to determine if drug testing after the accident was relevant. Gordon has said both he and Bobbi Kristina had been doing drugs and she took too much.

The Medical Examiner says he will not determine a cause of death until he reviews the records.