Frank T. Leber, 72, of Fox Lake.

A Fox Lake man has been charged with sexually assaulting two girls under the age of 13 over a span of several months while he was babysitting them, police said.

Frank T. Leber, 72, of the 0-100 block of Hawthorne Lane in Fox Lake, was charged with two counts of predatory sexual assault of a victim under 13 and four counts of aggravated criminal sexual abuse of a victim under 13.

Lake County Sheriff Spokesman Sgt. Christopher Covelli said sheriff’s detectives received a report that Leber sexually assaulted a child.

Detectives conducted a thorough investigation and learned that Leber committed acts of sexual contact with a child under the age of 13 on numerous occasions, according to a criminal complaint.

Covelli said that Leber did the same with another girl under the age of 13.

“He did this over the last several months while babysitting the children, whom he is related to,” Covelli said.

Lake County sheriff’s detectives obtained an arrested warrant on December 17 for Leber after a Lake County judge signed off on it.

Leber was taken into custody the same day the warrant was issued and was transported to the Lake County jail.

He remains held in the jail on a $750,000 bond and will need to post 10% — or $75,000 — in order to be released. He is scheduled to appear in court on Thursday for a status of attorney hearing.