CHICAGO (CBS) — Police in Kenosha, Wis., have been questioning a man in connection with the death of a woman whose body was found in a car trunk in the South Loop on Sunday.

CBS 2’s Susanna Song reports the body of a 30-year-old woman was found around 6:30 p.m. Sunday in the trunk of a 2004 Pontiac Grand Prix parked next to the Greyhound bus station in the 500 block of South Jefferson Street, below the Eisenhower Expressway.

The victim has been identified as Erin Ziemendorf. An autopsy conducted Monday by the Cook County Medical Examiner’s office found she died from blunt neck trauma and that her death was a homicide.

Chicago police said they got a tip from Kenosha police, after a man walked into the Kenosha station, and confessed he killed his girlfriend.

Police sources said the man claimed he and his girlfriend got into an argument in Wisconsin, and he accidentally killed her. He admitted to stuffing her body in a duffel bag, putting it in the trunk, and driving the car to Chicago. He then took a train back to Wisconsin.

Sources said the suspect told police the woman died after he pushed her to the ground.

Erin Ziemendorf’s pastor in Milwaukee, Ari Mattson, says she was a member of Martin Luther Lutheran Church since birth.

“We had children around the same age that would play around each other when they were both at church. My memories of her are as a caring mother.”

Pastor Mattson says the congregation is in shock that Erin Ziemendorf was killed.

Her boyfriend also attended church from time to time, a church member says.