Jose Ramirez has been charged with first-degree murder after he confessed to killing his parents Susan Brill de Ramirez and Antonio Ramirez Barron, and Matthew Roberts has been charged with the obstruction and concealment of their homicidal death. Picture: Peoria County Jail via AP

Peoria, Illinois — The bodies of a college professor and her husband have been recovered from a river in central Illinois and their 21-year-old son, who said he was "sick of his parents" according to authorities and stabbed them to death, has been charged with first-degree murder.

The bodies of Susan Brill de Ramirez and Antonio Ramirez Barron, both 63, were found Tuesday in the Spoon River near Annawan, resting against the riverbank, Peoria County Coroner Jamie Harwood said.

Jose Ramirez was arrested and charged on Monday after confessing to killing his parents, Peoria County Sheriff Brian Asbell said. Ramirez has been appointed a public defender and is being held on a $3 million (about R44 million) bond.

Judge Sean Donahue scheduled his arraignment for November 29.

Peoria County Assistant State's Attorney Dave Kenny said during a bond hearing on Tuesday that Ramirez told friends he was "sick of his parents" and that he had killed them on Friday.

Ramirez waited until his parents were sleeping then went into their bedroom at their home near Peoria, Kenny said. He used pepper spray as a distraction and stabbed his father in the stomach and neck, then stabbed his mother when she woke up, Kenny said.

Ramirez then wrapped the bodies in a tarp and a tent, put them in his father's SUV and drove about 50 miles (80 kilometers) to the Henry County community of Annawan, where he dumped them off a bridge into a waterway, authorities said.

Peoria County sheriff's deputies found blood and signs of a struggle in the family home Sunday after a call from a concerned relative, Asbell said.

The couple last reported to work on Thursday at Bradley University in Peoria, where Brill de Ramirez was an English professor and Ramirez Barron worked in the school's information technology department.

Another suspect, Matthew Roberts, 21, is now also charged with first-degree murder. Roberts had faced obstruction of justice and concealment of a homicidal death charges, but authorities said those were dropped in favor of murder charges after they determined he played a more active role in the killings.

A judge ordered Roberts, of Princeville, held on a $3 million bond on Wednesday. Roberts requested a public defender, which the judge granted because of his lack of income.

Court records don't list an attorney to speak on Roberts' behalf.

Peoria is about 130 miles (210 kilometers) south-west of Chicago.

AP