In the master bedroom, except for a stepping flower quilt on the bed (the quilt is obliquely covered on Mr. Liu's body), everything is neatly arranged, and all the cabinets have no signs of turning; There was no sign of the other two rooms being turned. In the living room, where the large sofa is near the balcony sliding door, there are two school bags (the balcony is on the south side of the living room; There are three large sofas, two small ones, and two small sofas are placed diagonally above the two ends of the large sofa.

Yan Jianhua and Li Wenhua only extracted a set of shoe prints from the living room and the master bedroom - the marks of slippers, which are still worn on Ma Wenjing's feet, when she entered the house, she changed into a pair of slippers, and after finding out that something had happened, she rushed out of the security door, and she didn't even have time to change the slippers.

The bathroom has been washed with water, and there is still some water left in the cracks of the non-slip floor tiles. There are also a few droplets of water on the wall tiles. There was a sponge mop in the corner of the bathroom, Liu Dayu twisted it with his hand, and there was still a lot of water on the sponge mop.

This indicates that the killer processed the footprints - the living room, the master bedroom and the bathroom - before leaving the scene.

Chen Jie and Liu Wenbin extracted several fingerprints from the doorknobs of the two small rooms, and after comparison, they were the fingerprints of Teacher Liu, Teacher Ma and two children. As for the first door, the door of the master bedroom and the door of the bathroom, there were no fingerprints taken - according to common sense, there should be Mr. Liu on the doorknob of these three doors. The fingerprints of Mr. Ma and the two children, the murderer disposed of all the original fingerprints when he erased his traces. This shows that the murderer has a certain sense of anti-reconnaissance and experience.

Let's take a look at three autopsy records.

First autopsy record:

The name of the deceased, Liu Xiaoyu, aged 61 (retired on November 9, 1995), died at about an hour and a half (the autopsy was at 6:05), and according to this calculation, the time of death of Mr. Liu was around 4:30. This is exactly the time when Chen Qiming gets out of school, and it takes about ten minutes for Chen Qiming to walk home from school (not including the time she was delayed on the road), which means that when Chen Ming returned home, his grandmother had already been killed. At this time, the murderer was processing the scene inside the house and preparing to leave. As a result, he was bumped into by Chen Ming.

By the way: Chen Qiming and Chen Qidi both have the keys to the house. Chen Qiming opened the door and just blocked the murderer in the room, in order to kill the murderer, the murderer poisoned Chen Qiming.

The source of death is in the neck, there is a rope on Mr. Liu's neck - it is a blue-colored nylon rope, the diameter is 0.7 centimeters, because the murderer is very strong, the rope is relatively thin, the nylon rope is deeply strangled into the flesh of the neck, untie the rope, there is a purple strangulation mark on the neck, the rope is buckled on the back of the neck, which shows that the murderer is from behind Mr. Liu, taking advantage of his unpreparedness, strangled Mr. Liu to death.

There were no scars on the rest of Mr. Liu's body, only the nail of his right index finger was somewhat worn, and there was some coffee-colored powder between the nails.

Chen Jie found a scratch 4.5 cm long on the back of the chair - the brown-colored paint layer on the scratch was no longer there, and it was supposed that the murderer strangled the rope around Mr. Liu's neck from behind, and Mr. Liu grabbed the back of the chair in order to struggle and maintain his balance.