WAUKEGAN, Ill. (CBS) — A suspect suddenly backed out of a plea deal Wednesday for attacking a cab driver who later died in Zion, claiming his religious beliefs exempt him from the law.

As WBBM Newsradio’s David Roe reports, prosecutors thought they had the case all sewed up. Darryel Garner, 40, had agreed to plead guilty to first-degree murder for the death of Zion taxicab driver Patrick Foster, the Chicago Tribune reports.

LISTEN: WBBM Newsradio’s David Roe reports

Garner is accused of shooting Foster several times after Foster picked him up in his cab on March 13, 2010. Foster, 45, died of his injuries a couple of months later.

But the Tribune reports in court Wednesday, Garner backed away from his agreement to plead guilty. His attorney told the court that Garner cited his religious beliefs as reasons why he doesn’t think he is subject to the laws of Illinois, the court or the judge.

But Garner’s religion was not revealed.

Garner’s attorney, Lake County Assistant Public Defender Keith Grant, said he was concerned about his client’s mental health and questioned his IQ, and said Garner was delusional, the Tribune reported.

Meanwhile, Garner’s decision not to plead guilty left Foster’s widow in tears, the newspaper reported.

The judge ordered a quick hearing on Garner’s mental fitness.

Police say Garner emptied his revolver into Foster’s neck, back and face. After he was shot, Foster lost control of his cab, which ran up on a lawn and almost plowed into Jim Hamm’s home on Lebanon Avenue.

Foster, 45, laid on the horn after he was shot. Then bleeding profusely, he climbed over the seat into the back of his cab, where police say he fought with Garner.

The two men spilled out of the cab onto the concrete.

“This driver must have fought with this guy for 10 minutes, at least,” Hamm told CBS 2’s Mike Puccinelli at the time.

Foster hit and subdued Garner, and called 911 and then his wife. Garner was arrested and charged a short time later.

The charges against Garner were upgraded to murder after Foster died.