3 Teens Charged With Sexual Assault At Saint Viator Graduation Party: Police

ROSELLE, IL — Following a six-month investigation, three teenagers have been charged with sexually assaulting a female classmate at a Saint Viator High School graduation party. The incident occurred in Roselle, according to the DuPage County State's Attorney's Office and the Roselle Police Department. The charges are as follows:

• Kevin Niemiec, 18, of the 700 block of E. Elaine Circle, Prospect Heights, is accused of 3 counts of criminal sexual assault
• Jon Clary II, 18, of the 1700 block of Ariana Drive, Bartlett, is accused of 3 counts of criminal sexual assault
• Zachary Mascolo, 18, of the 900 block of N. Beverly Lane, Arlington Heights, is accused of 2 counts of criminal sexual assault

A judge on Tuesday ordered Niemiec to remain detained, but denied the state's motion to detain the other two defendants. As part of their conditions of pre-trial release, Mascolo and Clary are not allowed to possess or consume alcohol, and also not have contact with the victim or her family.

According to prosecutors, Roselle police were notified of a criminal sexual assault that had occurred at a Saint Viator High School graduation party in Roselle the night before. Following an investigation, police said the alleged incident occurred when the three defendants and the victim were in a minivan, with each of the accused sexually assaulting the victim.

After the assault, the victim reportedly went to the home of a friend, contacted her sister, who in turn told their parents. Prosecutors said the victim's parents immediately picked up their daughter from the friend's house and brought her to a local hospital for medical attention.

Last Wednesday, Judge Michael Burton issued an arrest warrant for all three defendants. On Saturday, authorities took Mascolo into custody on his arrest warrant as he was driving near his home. Clary and Niemiec turned themselves in to the DuPage County Jail on Monday, according to prosecutors.

"The allegations levied against these defendants are extremely serious," DuPage County State's Attorney Bob Berlin said. "A graduation party is a celebration of accomplishments and the excitement of a bright future. It is alleged that Mr. Clary, Mr. Mascolo and Mr. Niemiec violated the victim in the worst possible way and inflicted a lasting harm on a young woman. It is my sincerest hope that the victim and her family receive the care they require and deserve to help them cope with this horrific event. I commend the victim in this case for her courage and strength in bringing this matter to our attention."

Niemiec is due back in court on Jan. 12, 2026, while Mascolo and Clary are scheduled for court appearances on Jan. 27, 2026.