now faces charges of aggravated battery after authorities say he bit and punched a prison guard Sunday night.
Yashesh Desai, of 3 Plover Court, appeared in DuPage County court Friday.
Prosecutors say Desai resisted leaving his "feces-smeared cell" when it needed to be cleaned, punching and scratching a sheriff's sergeant, as well as biting the officer's finger hard enough to break it, according to the Chicago Sun-Times.
Desai did not enter a plea to the new charge, the Sun-Times reported, which carries a possible 5-year prison sentence.
During Friday's court hearing, Desai's arms and legs were shackled to a metal restraining chair and he was surrounded by a dozen DuPage County sheriff’s officers, the Sun-Times reported.
Desai was indicted Sept. 8 with five counts of first degree murder. Police say Desai killed his father, Sanjiv Desai, Aug. 14 by beating him in the head with a weed trimmer.
DuPage County State's Attorney Robert Berlin said in August he had "reasonable belief" Desai would raise the defense of insanity or plead guilty and mentally ill to first-degree murder.
Berlin said Desai talked about Godzilla, X and Y chromosomes and "killing the retards" in statements to police. Those statements led authorities to file a motion for an appointment of a clinical psychologist.
Desai's psychological evaluation had not been completed as of Sept. 23, when his arraignment had been scheduled. That arraignment has been pushed back to Oct. 28 to wait for the results.
According to Facebook, Yashesh Desai graduated from Downers Grove North High School and studied chemical and biomolecular engineering at the University of Illinois in Champaign-Urbana.
He was dismissed from the University of Illinois after he waved a knife at fellow students and was charged with aggravated assault, the Chicago Tribune reported.
Reports have said Desai and his father argued about money before the alleged killing. Patch has found that the family's home was in foreclosure, but no other financial issues were apparent in court records.
Just hours before police found Sanjiv Desai dead, a Facebook user registered as Yashesh Sanjiv Desai published dozens of comments on his page, including a list of weapons he said he needed and another post in which he said he'd "lost faith in humanity."
He posted close to 40 statuses in as many minutes between around 4:40 and 5:20 p.m.
responded to the scene about 3:07 a.m. Aug. 14 after a person had called 911 stating that his brother had just killed their father, according to a release from the DuPage County State's Attorney's Office.
Police found Sanjiv Desai lying on a futon in the computer room of his house, the release said.
"Desai was suffering from massive head wounds. He was taken to a local hospital where he was pronounced dead as a result of the injuries he sustained," the release said.
Sanjiv Desai was allegedly sleeping on a futon in the computer room of his home when Yashesh Desai struck him multiple times in the head with a weed trimmer, the release said. That resulted in severe trauma to Sanjiv Desai’s head.