Graduate student Jelani Day’s cause of death was drowning, according to LaSalle County Coroner Richard Ploch, but how Day got into the Illinois River remains “unknown,” CNN reports.

The 25-year-old Illinois State University student was last seen on Aug. 24. His body was found in the river on Sept. 4, and identified later in the month. "There was no evidence of any [pre-death] injury, such as manual strangulation, an assault or altercation, sharp, blunt, or gunshot injury, infection, tumor, natural disease, congenital abnormality, or significant drug intoxication,” Ploch added.

Day’s case, which the public began to call for greater attention following the media attention surrounding Gabby Petito, will involve at least two autopsies: one by the coroner and one by a family-hired independent private forensic pathologist.

Day’s mother, Carmen Bolden Day, said she disagrees with the coroner and believes someone is responsible for her son’s death, sharing that she feels there’s a “narrative that my son did something to himself.”

“Somebody did this to him, and they are going to be held responsible for doing what they did to my son,” she said, per CNN.

Rev. Jesse Jackson Jr. also disagrees with the coroner’s findings, and called them a “suicide line.” Members of the Illinois State Black Student Union intend to march Tuesday in front of the police department in the city of Peru where Jelani’s car was found on Aug. 26. 

“Jelani, if you would have met him, anybody under the sound of my voice that would have met him, you would have loved Jelani,” Bolden Day previously told CNN. “Jelani was very driven, outspoken, but also he was the most caring, compassionate, protective son, grandson, brother, friend, cousin, nephew that you would have wanted to have. Jelani was one of a kind.”