CHICAGO (WGN) — The FBI is offering a reward of up to $10,000 for information regarding the death of Jelani Day.

The Illinois State University graduate student was reported missing Aug. 25 after he failed to return messages from a professor and family. He was last seen on the Normal, Illinois, campus Aug. 24.

Day’s car was found in Peru, Illinois, two days later about 60 miles north of Bloomington, and his body was discovered in the Illinois River on Sept. 4 in the LaSalle-Peru area.

A coroner determined in October that Day died from drowning, but said it was unclear how the 25-year-old wound up in the Illinois River. LaSalle County’s coroner said an autopsy on Day found no evidence of “manual strangulation, an assault or altercation, sharp, blunt or gunshot injury.”

Carmen Bolden Day said she believes her son was “murdered” and she wants to know who is responsible and why it happened. She helped push the FBI to get involved.

Anyone with information about Day’s death is urged to contact the FBI or the nearest American embassy or consulate.