A teacher's mother-in-law and sister-in-law have been arrested for hiring a man to kill the teacher in northwest China's Gansu Province after a hunt that involved his school's 2,000-plus teachers and pupils.

The suspect is arrested by police.

The popular physics teacher, surnamed Ma, 37, was stabbed to death on March 4 in Pan'an Town, Gangu County of Gansu's Tianshui City, Xinhuanet.com reported.

In an online post, the school principal asked the 2,400 teachers and students to join the police hunt and hunt for clues to help solve the case.

Eight days later police caught the suspected killer Yao, 29, on a train traveling to south China. They also caught Ma's mother-in-law, surnamed Zhang, 62, and sister-in-law, surnamed Xian, 30, whom Yao said had given him 5,000 yuan (US$731) to kill Ma.

Yao, Zhang and Xian were detained on March 14 and charged with murder.

Angry students threw chalk at the three when police escorted them through the school.

Zhang and Xian told police they began hating Ma after Ma's wife died. They said Ma's wife had poisoned herself after a fight with him in 2004.

The women found the unemployed Yao in February and asked him to "give Ma a lesson" and offered him 10,000 yuan. But they delayed the plan because police conducted a security clampdown during the Spring Festival holiday.

Yao said he had received 5,000 yuan from the women before the attack.

Yao told police he had taken Ma to dinner on March 4, pretending he wanted Ma to help enroll a friend's child at Ma's school. After the meal, he lured Ma to a dark alley and stabbed him three times. Aided by the two women he then fled to south China.

(Shanghai Daily March 17, 2009)