The murderer is Runyi. He Quanyuanzi called his brother on Friday night and told him that he was in a bad mood and wanted to go back to his hometown to meet his brother and Quan Kangzheng. He and Quan Kangzheng waited for two days without seeing his sister, and then they came to the home where her sister lived. At this point, her sister has no breath.

The cause of death was electric shock, that is, two wires of an electric blanket, one connected to the chest, the other connected to the back and connected to a timer switch. Time is up (1), the current passes through the heart and dies instantly.

According to his sister's cleanliness, untidiness in the room, plastic strings in the corner, corks with screw bottle openers on the ground and unlocked door chains, he judged that his sister did not commit suicide, but he killed her. So after collecting some evidence, I called the police to avenge my sister.

Extended data:

Who killed her is a mystery novel by Japanese writer Keigo Higashino, published by Toastmasters Japan in June, 1996. 1999 Library was published by Talk Club in May. Who killed her is the third part of Kaga Kyouichirou's detective stories. The last work in this series is Sleeping Forest. The next work is malicious. Mainland edition of Who Killed Her, published by Nanhai Publishing Company on 20 12. Taiwan Province Provincial Edition was published by Dubu Culture Press 20 12.

Creative background: In the novel Guess Who the Prisoner is, there are two suspects. Based on this view, Keigo Higashino had a preliminary idea about the story "Who killed her". At the same time, Keigo Higashino thinks that novels that can make readers make self-reasoning in reading are called mystery novels.

However, according to the general writing, readers can't make inferences themselves, which I also wrote in "The Password of a Detective". After careful consideration, I finally came up with this technique, or decided to use it.

Reference: Baidu encyclopedia: Who killed her?