Vance Nwankwo, 25, went missing last week after leaving a Schaumburg nightclub. Family members say Nwankwo has a mild form of autism.
Dive teams were searching the pond near Nwankwo's home.
Nwankwo has been missing since a cab driver reportedly brought him home from an October 30 Halloween party. He was last seen dressed as the Incredible Hulk for a costume party. Nwankwo was painted green, including his hair and beard. Nwankwo was wearing khaki pants and a white t-shirt that was ripped.
Although investigators say there is no indication any foul play was involved, friends and family suspect someone may have lured Nwankwo away from home.
Nwankwo was reported missing by his mother November 1.
Fire department teams used side-scan sonar to search the pond behind the home Nwankwo shares with his mother. Nwankwos's father died several years ago.
According to police, a cabdriver drop them off Nwankwo in front of his home after picking him up from the Drink nightclub in Schaumburg nightclub. Detectives say the man's boot was found near his home's mailbox, possibly indicating that he made it home.
Nwankwo is described as of African descent. He is 6'2" and weighs about 192 pounds. Friends say he has a slight stutter and is a kind and loving person.
"At this point, we don't think any foul is involved. We think he's just missing," said South Barrington Police Chief Mike Deegan. "But we haven't been able to locate any indication of where he's at or where he's gone to. We did have the Secret Service did check his cell phone record and there is no indication of any phone calls coming in or going out after he went missing. Obviously there's a lot of phone calls coming in because people are trying to get a hold of him."
Friends said, if they cannot locate Nwankwo Friday, they plan to form their own search parties and begin to look at the field around his home and South Barrington.
A Facebook page has been set up to help locate the man as his family continues to hope for the best.
Police are asking anyone with information to call them.