A 14-year-old boy in Xi'an, the capital of Shaanxi province, killed his 18-month-old sister and told police he did not regret doing so, Huashang Daily reported on Tuesday.

Surnamed Sun, the boy lived with his grandmother and younger sister in a village in the city's Yanliang district. At about 6 pm on Sunday, he asked his grandmother to go out to buy him something and, while she was gone, killed his sister with a knife. The boy then went to a shop his parents run in the district at about 7 pm and told his father he had killed his sister. The father called the police.

Sun's classmates in a junior high school in the district said Sun was introverted and seemed not to like his sister as he thought she took most of his parents' love.

Police detained Sun and, as he is only 14 years old, asked some villagers to take part in his questioning. Sun told the police he killed his sister and answered four times that he did not regret the action.

Hu Baohua, a local psychological expert, said children at such an age are psychologically immature and can feel ignored and neglected by their parents when the family has a second child. A local lawyer said a boy of Sun's age should bear the corresponding criminal liability in accordance with the law.

The case is under further investigation.