A special prosecutor has been appointed in a case where a Joliet police officer was charged with driving under the influence in connection with a crash on Interstate 55 that killed a Berwyn police officer.

Officer Erin Zilka, 35, who also faces a charge of failure to reduce speed, has been placed on administrative paid leave while she is investigated by internal affairs and Illinois State Police, Joliet police Sgt. Christopher Botzum said.

The Plainfield resident crashed into the back of a box truck that had been involved in a wreck with a Nissan Titan pickup a short time before, state police said. The crash occurred about 6 a.m. Sunday on Interstate 55 north of Route 30.

Berwyn officer Charles Schauer, 33, of Glen Ellyn, who was in Zilka’s car, was pronounced dead at the scene of the crash, state police said.

State Trooper DeAnn Falat said the fatal crash remains under investigation. When asked Tuesday what substance Zilka allegedly had in her system, Falat said, “Until the test results come back, I don’t have any other information.”

On Tuesday, Will County State’s Attorney James Glasgow filed a motion to have a special prosecutor appointed because Zilka is a police officer and a “victim in a felony aggravated battery case” related to her job. She also is a witness in another criminal case, according to the motion.

Zilka is scheduled to be arraigned March 18, said Carole Cheney, a spokeswoman for the Will County State’s Attorney’s Office. Zilka was released from custody on her own recognizance, court records show.

Rodrigo Marin, 42, of Plainfield, who was arrested on probable cause of aggravated DUI in the same incident, is being held at the Will County jail on a $250,000 bond.

Marin was also arrested on probable cause of failure to reduce speed, improper lane use, leaving the scene of an accident, failure to render aid, no valid insurance and driving on a revoked license, state police said.

No formal charges appeared to have been filed against Marin as of Tuesday.

Marin lost control of the Nissan Titan for “unknown reasons” and struck the 2008 box truck, according to state police.

Marin then left the scene of the crash but he was later found on foot not far away, according to the state police.