ST. CHARLES (CBS) — The glare of the sun off passing motorcycles caused Alia Bernard to reach for her sunglasses on the May 2009 morning when she caused a chain-reaction crash that killed a west suburban couple.

But it was the marijuana — consumed three or four days earlier, according to her attorney — found in her blood system that has the 27-year-old Aurora woman facing a minimum of six years in prison after she pleaded guilty Friday to two counts of aggravated DUI.

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In a sometimes trembling voice, Bernard, 27, of the 1500 block of West Galena Boulevard in Aurora, admitted she had marijuana in her system, according to prosecutors.

Judge Allen Anderson accepted her guilty plea and set sentencing for Feb. 8. Although Bernard faces up to 28 years in prison, Anderson can sentence her to probation or a lesser punishment if he finds exceptional circumstances as to why she should not be imprisoned.

Bernard’s attorney, Bruce Brandwein, said he would argue for the lightest sentence allowable.

“She has no background, there’s no impairment here,” Brandwein said, noting prosecutors agreed that she was not high at the time of the crash.

About 8:20 a.m. on May 23, 2009, at the intersection of Route 47 and Smith Road south of Elburn, a vehicle in the southbound lane on Route 47 had stopped to turn left onto Smith Road, waiting for several northbound motorcycles to pass, according to the release.

Two additional southbound vehicles stopped behind it when a 1999 Toyota Solara driven by Bernard, approached and struck the third vehicle in the rear. The collision created a chain reaction that ultimately pushed the first vehicle into the path of the oncoming motorcycles.

A 2000 Harley-Davidson Softtail struck the third vehicle, the motorcycle’s driver, Wade Thomas, 44, of St. Charles, and the passenger, his wife, Denise Thomas, 45, also of St. Charles, were killed.

Prosecutors initially charged Bernard with two counts of reckless homicide, claiming she failed to “keep a proper lookout” prior to the crash.

Court documents also state Bernard texted someone around the time of the crash and that she failed to slow down or brake to avoid the crash because she took her eyes off the road to grab sunglasses and put them on.

Bernard became vulnerable to the more serious charges after an April Illinois Supreme Court decision ruled that prosecutors did not have to prove impairment was a “proximate cause” of a fatal crash, but just that defendants have any amount of a drug in their systems. That decision prompted prosecutors to upgrade charges, and potential penalties, against Bernard.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2011. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)