CHICAGO (CBS) — New details emerged Monday about charges against a suburban police officer involved in a deadly crash.

The off-duty Joliet officer’s attorney said Illinois State Police reported her blood alcohol level was below the legal limit. But Erin Zilka was still charged with driving under the influence.

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Zilka is accused in a crash early Sunday on southbound Interstate 55 just north of Route 30.

Erin Zilka, a Joliet police officer, is charged with DUI in a crash that killed Berwyn Police Officer Charles Schauer. (Credit: Illinois State Police)

The crash took the life of 10-year veteran Berwyn police Officer Charles Schauer.

Officer Charles Schauer

Berwyn police Officer Charles Schauer was killed in a traffic crash. (Credit: Berwyn Police)

CBS 2’s Tara Molina discussed the case against Zilka with CBS 2 Legal Analyst Irv Miller – who explained that Zilka can be charged with DUI for more than blood alcohol content alone.

Schauer was a passenger in a Dodge Durango that Zilka was driving, according to Illinois State Police. It slammed into the back of a box truck and left Schauer dead almost instantly.

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A witness said he saw Zilka get out of the car, and he recorded her walking right after the collision.

Zilka was charged with DUI and driving too fast for conditions. But Miller said the charges could change.

“Frankly, it really doesn’t make any difference what she was charged with today, because down the road, the prosecutor can do one of two things,” Miller said. “He can lower the charge to reckless driving, or if he thinks it’s a felony, he can raise it.”

While Zilka’s attorney said her blood alcohol was below the legal limit, the Will County State’s Attorney’s office won’t comment on the matter.

But the State’s Attorney’s office did say blood alcohol is not the only reason someone can face a misdemeanor driving under the influence charge. There could be more to consider.

“It indicates to me that the officers who responded to the crash thought that the driver – the lady police officer – was under the influence of alcohol. And abased upon the impairment show showed – whether it be by her verbal responses being slurred speech or anything like that, or perhaps her walking was not in a straight line, her balance was off,” Miller said.

Illinois State Police were still investigating the crash and the role conditions played in it late Monday.

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Zilka is scheduled to be in court in March.

Tara Molina