Police in Evanston said they were working with the FBI to examine information stored on the victim's computer, the Chicago Tribune reported.
The headless body of Colin Dalebroux, 21, was found near Fitzsimons Park by a man walking his dog before dawn Tuesday.
Hours earlier, an explosion ripped through the park, shaking nearby homes and waking residents.
Authorities thought a transformer had blown and searched the area but nothing turned up until Dalebroux's body was discovered.
Resident Dale Wyatt said at first he thought it was a mannequin and some kind of "sick joke" but a closer examination revealed a shirtless man wearing pants with his legs folded underneath him and his right arm stretched up.
The Cook County sheriff's bomb squad disabled an unexploded pipe bomb found near the body.