Police in the US say a girl (14) confessed to stabbing to death her sister (11) in Illinois because the little girl had been ungrateful.

The victim, identified as Dora Berancourt, was knifed 40 times in her chest, neck and arms.

The 14-year-old has been charged with murder and will be tried in a juvenile court, as police keep probing the case.

The prosecution said the older girl set the alarm early so she could get to her sister while she was still in bed in their home in Mundelein, a small town just outside Chicago.

She took a knife from the kitchen and went to her sister's bedroom. With each strike of the knife, prosecutors said, the suspect yelled reasons for her attack.

The girl told prosecutor she was furious because she had performed several domestic duties, such as making dinner, and her sister had been ungrateful.

She was also angry because Dora had hit her the night before, she told prosecutors. Officials said the girls' mother, the only adult living in the home, was at work when the stabbing took place.

The woman cried at a court appearance where details of the case were given.

The next court appearance is set for January 31st. The Chicago Tribune reported that a group of women in Mundelein are raising funds to help the family.