Sgt. Jeff Pelo, a 17-year veteran of the Bloomington Police Department, wore a blue jail jumpsuit and was flanked by sheriff's deputies during the brief hearing. He signed "I love you" to his wife before leaving court.
The alleged assaults started in 2002. In the last, in January 2005, Pelo is accused of raping the woman twice and repeatedly assaulting her.
A McLean County grand jury indicted him on 35 counts including aggravated criminal sexual assault, intimidation, residential burglary, home invasion and aggravated unlawful restraint. The assailant used a knife in one attack and a gun in another, and prosecutors say he threatened to harm the family of the last accuser if she contacted police.
If convicted, prosecutors said Pelo could spend the rest of his life in prison.
Defense attorney Steve Skelton has called the state's case flimsy and said DNA evidence would clear his client.
Police said they found a mask, pry bar and other items in Pelo's home that appeared to have been used in at least one of the assaults. Prosecutors also say three of the accusers identified Pelo from photo lineups and two identified him by voice.
Pelo, now jailed on more than $2 million bond, is on paid administrative leave and still collecting his $81,000 annual salary.
He pleaded not guilty last month to charges stemming from an alleged break-in attempt at a woman's home a day before he was arrested. Prosecutors say police found Pelo lurking outside the woman's Bloomington home after she reported a late-night break-in attempt on June 10. Pelo told the officer he was out looking for a home for his mother-in-law.
The Bloomington area, 115 miles southwest of Chicago, is home to Illinois State University and Illinois Wesleyan. No details about the four women, including their ages and locations, have been released.