The apartment building is located in the 600-block of Grove Street in north suburban Evanston.
Police say a person of interest is being questioned in the case. That person was picked up on the street close to where the incident took place.
Police say sexual abuse is not the only crime that the offender allegedly committed Sunday morning. The suspect also allegedly burglarized MBA student Justin Shuman. Both incidents took place in a downtown Evanston apartment building early Sunday morning.
"I was away Saturday night when my apartment was burglarized. They stole sunglasses, i-Phone and my car keys," said Shuman.
Five hours later police received a 911 call from a Northwestern Student who says she was sexually abused.
"The victim was sleeping in her bed and that the offender entered through an unsecured window, and then approached her while she was in her bed and began to fondle her," said Commander Tom Guenther, Evanston Police Department.
Police say the female student was able to give a very detailed description of the offender, which Shuman says helped in his burglary case as well.
"The young lady provided a description...she said she bit his hand. They found a gentleman, his hand was bitten, fit the description and he had my car keys on him," said Shuman.
In the sexual abuse case, the offender was able to get into the apartment building through an unsecured window. Shuman believes, though, that five hours earlier the suspect was able to get into the building when his apartment was burglarized through the front door. He says they have been having problems with the front door which hasn't been locking properly. Shuman has alerted the management company. ABC7 contacted the management company but they did not have a comment.