NORMAL, Ill. (NewsNationNow) — Jelani Day’s family held a march in his honor Tuesday in the city of Peru, Illinois, demanding justice and answers in his death.

Day’s mother, Carmen Bolden Day, the Rev. Jesse Jackson and members of his Rainbow Push Coalition rallied outside the Peru Police Department. They also visited key sites, including the woods where investigators found his car and the site where they discovered his clothes.

“There’s no way my son would’ve known about this,” Day said. “He wouldn’t have put his car here, he wouldn’t have taken his license plates off. He wouldn’t have gotten out of his car and walked three miles to the river.”

Day, 25, was last seen Aug. 24. His family in Danville and a university faculty member reported him missing after he did not show up for class for several days. Day’s car was found Aug. 26 in a wooded area in Peru, about 60 miles north of Bloomington. His body was found in the Illinois River near the city Sept. 4.

Jackson spoke to Illinois State University’s Black Student Union on Monday night. He made it clear that he believes Day was murdered and that his suspected killers are still wandering free.

“The persons that killed Jelani Day are alive tonight, walking the streets among us,” Jackson said. “Whoever killed him, let the record show it.”

Jackson said he doesn’t think local investigators can be trusted with this case, and he’s calling for the state’s attorney general, the FBI, the Department of Justice and President Joe Biden to all get on board with the investigation.

On Monday afternoon, LaSalle County Coroner Richard Ploch released the official cause of Day’s death as drowning.

Ploch also stated that there was no sign of any antemortem injuries, such as manual strangulation, an assault or altercation, sharp, blunt, or gunshot injuries.

Both Jackson and Day said they don’t believe the findings, and Day said her son was strong and he wouldn’t harm himself.

“No, Jelani didn’t hurt himself, no, Jelani didn’t drown himself,” Day said. “No, Jelani didn’t do this to himself. Somebody did this to Jelani.”

A multi-jurisdictional task force including the Illinois State Police, the Bloomington and Peru police departments, LaSalle County Sheriff’s Office and the FBI’s behavioral analysis unit continue to investigate Day’s death.

NewsNation afflicate WMBD contributed to this report.