Below, let's take a look at the situation of Liu Dayu, Liu Wenbin and police officer Wang Dequan along the way:

Directly opposite the staircase of Unit 3 of Building 5 is Wang Baoting's barber shop. To the west of the barber shop are Liu Donghan's baked cake shop, Dai Shunfeng's dried noodle shop and Ma Guimin's fried food shop, and to the east of the barber shop are Chai Linping's flower shop, Tang Erli's fruit shop, Fei Yuxiang's dental clinic and Li Yongjian's hardware shop.

On the afternoon of the day of the incident, because of the rain, there was no business at all, and everyone gathered at Liu Donghan's baked cake shop to play mahjong -- when business was light, everyone gathered at the baked cake shop to play mahjong, and 20 yuan went into the garden, and there were two tables at one table.

Everyone's attention is focused on the mahjong table, and they don't particularly care about the people who pass by the shop and enter and exit the vegetable market, let alone the people who enter and exit the staircase of the third unit of Building 5?

The murderer should also be very familiar with this situation, only when everyone is playing mahjong, he can enter and exit the third unit of Building 5 under the noses of everyone, if everyone sits in the store and waits for business, they will pay special attention to everyone who passes by the door of the store - as long as the person passing by the door of the store may be their customer, so many pairs of eyes, the murderer must be difficult to hide.

The bosses were shocked that such a big murder happened in Mr. Ma's house, and they were even a little annoyed and blamed themselves, the murderer lowered his nose and went freely, but they didn't know it. It is precisely because they all gathered at Liu Donghan's house to play mahjong that the murderer is like no one.

You've heard it! Liu Dayu's investigation and visit along the way found nothing. At the end of the investigation, Chen Jie came all the way, Aunt Hao once mentioned a situation, Mr. Ma's lamp is broken, we all know, the lamp is broken, either the fuse is broken, or the bulb is broken, or it may be a problem with the wiring, no matter who Mr. Ma asks to repair, some materials must be bought, there is a hardware store downstairs, will Mr. Ma go to this hardware store to buy things?

When Chen Jie raised the question, Li Yongjian, the owner of the hardware store, immediately remembered one thing: at about two o'clock yesterday afternoon, Mr. Ma once went to his hardware store to buy two 12-watt energy-saving light bulbs and a gusset - that is, the plastic gusset used for the ceiling, from Mr. Ma's very incoherent description, it seems that the bathroom light is broken - it is a problem with the wiring, the wire is on the top of the gusset, the electrician takes down the plastic gusset, and it can no longer be installed, once this kind of gusset is installed, it is difficult to take it down again. The broken gusset must be replaced again, Mr. Ma went to Li Yongjian's hardware store to try it, the color of the gusset is almost the same, but the pattern on it is somewhat different, Mr. Ma does not want to bother, so he bought a gusset in the hardware store of Li Yongjian.

Li Yongjian also mentioned a very important situation: Yesterday afternoon, Mr. Ma went to the bank first, and before going to the bank, he stayed in his hardware store for a while, at that time, he was carrying a bag in his hand -- it was a black handbag, Mr. Ma first told Li Yongjian about the light bulb and gusset, and also paid first, saying that he would take the things home when he came back from the bank.

Li Yongjian also mentioned a detail: When Mr. Ma came back to pick up his things, he carried a black handbag on his right shoulder -- the handbag could be carried as well as carryed, and Li Yongjian noticed that when Mr. Ma came back from the bank, the leather bag was heavier than before -- when Li Yongjian first met Mr. Ma, the bag was carried in his hand.