According to China officials the victim, identified as Jiang Xiaoling was killed by Zhang Xuezhong as he was angry with her for forcing his wife to abort their child.
Jiang's husband, Zhao Guogui, who is also a farmer said that assailant barged into his house with a stick in his hand and beat his wife to death.
He also attacked his son, 15, and daughter, 11, with the stick. Both of them have been rushed to the hospital.
Hospital officials said that the girl has slipped into coma and has been placed in the intensive care unit.
Zhao said that the Zhang was angry because Jiang had reported that Zhang's wife's pregnancy was against the rules of family planning in the country.
"He is so ruthless. My wife reported to the superiors that his wife was unlawfully pregnant again," Zhao was quoted as saying by Global Times.
In Feb 2010, Jiang found out that Zhang's wife was pregnant and she tried to convince her to abort her baby, to which the couple protested.
Jiang then reported the matter to the higher officials, following which Zhang's wife underwent the abortion.
Family Planning Policy in China allows farmers to have a second child only if the first one is a girl or has a disability.
Zhang has been earlier been imprisonment for 13 years for attempting to kill his father-in-law.