While investigating a possible attempted child abduction, Calumet City police on Wednesday arrested a sex offender on unrelated charges.

Dennis Lane Richardson, 42, of Calumet City, was charged with felony failing to register as a sex offender in Illinois, according to police records.

But police still are looking for a different man who offered a girl a ride home from school Wednesday, Calumet City Capt. Dan Zorzi said. The incident happened near Schrum Memorial School on Gordon Avenue.

"We are still looking and still investigating that incident," Zorzi said.

The suspect is a white man in his 40s who was driving a light-colored minivan.

"All he said was, 'Do you need a ride?' but we take (those things) seriously," Zorzi said.

Richardson denied attempting to lure the child, and police determined he was not responsible in this incident, Zorzi said.

Richardson is listed in the Indiana Sheriff's Sex and Violent Offender Registry. He was convicted of child molesting and sentenced to six years in 1996. In 2005, he was convicted of child solicitation and sentenced to three years in the Department of Corrections, according to the registry.