Janet Strickland, 64, and her 19-year-old grandson William Strickland, are accused of plotting to kill her 72-year-old husband, also named William, as he headed to dialysis treatment, the Chicago Tribune reported.
Prosecutors said that after the younger William killed his grandfather in the street with a gun he stole from him, he and his grandmother used the grandfather's savings to buy a car, home furnishings, tattoos, gym shoes and other items.
The 19-year-old, who allegedly shot his grandfather six times in the back, was charged March 30 with first-degree murder and armed robbery, the newspaper said. He was being held without bond.
Janet Strickland was arrested Thursday and charged with first-degree murder and armed robbery.
She missed her court appearance Saturday where her bail was set at $500,000 because she was in a hospital being treated for lung disease and low oxygen, the Tribune said.
Prosecutors allege she had told her grandson she was "sick" of her husband and that she wanted him dead.
"She stated ... that she wished he was not here and she wanted him gone," Assistant State's Attorney Jacqueline Kwilos said during her bond hearing.
Kwilos said the two discussed hiring someone to carry out the killing but the grandson decided to do it himself, the Tribune said.