Tree-Hanging Death on Campus Ruled Suicide by Mississippi Officials

The autopsy for De'Martravion "Trey" Reed -- a black student found hanging from a tree this week at Delta State University -- has been completed ... and officials have determined his manner of death was suicide.

The Cleveland Police Department announced an autopsy performed by the Mississippi State Medical Examiner's Office was "consistent with the initial investigation, determining the cause of death to be hanging and the manner of death as suicide."

Final toxicology results are still pending, and can take between 2 and 4 weeks, police noted. They also said "all files and investigative material" have been sent to the FBI and the U.S. Attorney's Office for further review.

As we reported ... the 21-year-old student was found hanging from a tree on campus Monday, and law enforcement said foul play was not suspected. Reed was from Grenada, The Clarion-Ledger reports ... the newspaper reports another man, 36-year-old Cory Zukatis, was found dead, hanging from a tree, on the same day, about 100 miles south of Delta State in an unrelated case.

Attorney Vanessa Jones, who is representing the Reed family, raised some eyebrows when she claimed Trey's relatives were originally told he was found deceased in his dorm room and had been left largely in the dark about the investigation.

TMZ has reached out to Jones for comment ... so far, no word back.