SYCAMORE – Prosecutors filed additional charges Thursday against a former Energym gymnastics instructor that could send him to prison for life after investigators identified four additional victims.

Joseph R. Hannon, 21, formerly of the 1700 block of DeKalb Avenue, Sycamore, was charged Thursday with three counts of aggravated criminal sexual abuse and a single count of predatory criminal sexual assault of a child. If Hannon is convicted of predatory criminal sexual assault of a child involving more than one victim, state law requires he be sentenced to life in prison, First Assistant State’s Attorney Stephanie Klein said.

The new charges bring the total number of victims to six, all of them students at Energym in Sycamore.

Hannon has been in custody at the DeKalb County Jail since Dec. 7, when he was arrested on charges that he sexually abused a 9-year-old girl during an open gym session Nov. 25 at Energym. That incident was captured on video, police said. Later that month, prosecutors filed more serious charges related to a second victim.

Since then, investigators have done additional victim-sensitive interviews with Energym students. From those interviews, police found that Hannon had inappropriate physical contact with four other children while working at Energym in Sycamore.

“We continue to investigate this case so we may identify any additional victims, provide them the necessary resources and support while holding the suspect accountable for his actions,” Sycamore Police Chief Glenn Theriault said Thursday.

Klein said all of the victims were girls younger than 13.

When Hannon first was arrested, prosecutors said he might have inappropriately touched as many as 30 children.

Energym owner Andy Morreale has previously said Hannon was hired without a background check. Hannon had been arrested several times in DeKalb County and was on felony probation for an October 2013 drug case when he was hired. Hannon had taken classes at Energym, which has locations in Sycamore and Genoa, as a child. Energym hired him part time in September 2015 as a student instructor. In August, he was hired full time. In addition to employing Hannon, Morreale also rented an apartment to him near the gym.

The family of a girl who police believe was abused by Hannon has filed a civil suit against Energym Gymnastics Inc., Morreale and Hannon. The suit alleges that Energym and Morreale were negligent in hiring Hannon, that they failed to properly supervise him and bear responsibility for what happened to the girl because the incidents occurred at Energym.

Hannon remains in jail in lieu of $2.25 million bond, according to court records. He would have to post $225,000 to be released.

A preliminary hearing is set for March 17 in the criminal case.