The suspect is accused of attacking her sister, Dora Bentancourt, in the bedroom of her suburban Chicago home Jan. 21, stabbing her dozens of times with a kitchen knife, the Chicago Tribune reported.
Mourners at the victim's funeral Wednesday described the relationship between the sisters as loving and close, and several praised the girls' mother, who was at work at the time of the attack, the newspaper said.
One unidentified mourner said the single mother was doing her best to provide for her family, and called her strength in dealing with the incident an example for the community.
Police and prosecutors allege the older girl, upset over an argument, attacked her sister in bed, then called police claiming an intruder was responsible.
Attorney Michael Conway Friday requested a psychological evaluation for his client.