Three underage suspects convicted of robbing and killing a pair of campus sweethearts and then raping the body of the girl were sentenced to between 15 years and life in jail, the Beijing No 1 Intermediate Court ruled on Friday.

There were four suspects involved in the crime, one man and three minors.

The three underage suspects are a 17-year-old boy from Liaoning province, and a 16-year-old boy and a 15-year-old boy both from Hebei province.

The verdict follows a previous ruling by the court on Dec 7 to sentence the 20-year-old principle offender, Teng Xianhe, a man in his 20s and from Liaoning province, to death. He was also fined 1.02 million yuan.

According to the verdict, the 17-year-old was convicted of robbery, rape and molestation, and theft, and sentenced to life imprisonment. The 16-year-old boy was also convicted of robbery, molestation and theft, and sentenced to life. They were told to compensate the families of the victims with 780,000 yuan.

The 15-year-old was convicted of robbery and sentenced to 15 years, a lower punishment because of his young age. His family was ordered to pay 80,000 yuan.

The two victims were Wang Yuxin and Xin Xue, first year students at the North China Electric Power University.

Teng and the two oldest minors had been working as security guards at a building material market in Beijing, but were fired for theft and idleness, the Beijing Times reported in April.

On April 8, Teng and the three minors hid in a forest armed with knives.

When they found the couple in the forest, the gang approached them and stole 100 yuan and two mobile phones. Under instruction from Teng, the 15-year-old then killed the girl by stabbing her several times in her chest and arms. The three minors followed the violence by stabbing the boy to death.

The girl's body was then raped by two of the minors and Teng.

On Apr 11, Teng and the oldest of the minors were arrested in an Internet cafe in Haicheng, Liaoning province by Beijing police. The other two were then arrested in Handan, Hebei province.

The father of the male victim said he dared not think about his son.

"The four suspects all should have been sentenced to death, especially the three underage kids. They were even crueler than normal adults," the Beijing News quoted him as saying.

"We are from the countryside and the economic condition is bad. My family had expected my son to have a bright future after studying in Beijing," he said.