The second possibility is that Chen Qiming walked into the bathroom and just untied his belt, but the murderer covered his mouth and pressed into the bathtub. Comparatively speaking, the second type may be larger, and the belt is very likely to be tied by the murderer, and time does not allow the murderer to completely tie the belt and straighten it out.

Most of the long nails of Chen Qiming's left little finger are broken, and only about two millimeters are connected to the nails, which shows that Chen Qiming had struggled for a period of time when he was pressed into the bathtub by the murderer.

Chen Hongxiang said that both daughters have a habit of having long nails (limited to the smallest fingers).

Chen Jie carefully examined the inside of the nails, but there was nothing in the nails.

Chen Qiming's death time was slightly later than that of Mr. Liu, about twenty minutes, and Chen Qiming's armpit still had some residual warmth. This means that the time of Chen Qiming's death was around 4:50, which is more consistent with the time when she returned home after school.

Chen Qiming had not been sexually assaulted before his death, and the murderer's purpose in coming to Mr. Ma's house was very clear - he came for 260,000 yuan.

Finally, let's take a look at Chen Qidi's autopsy report:

Chen Qidi's body lies on the left side of the bathtub against the wall - that is, behind the fixed glass sliding door (although the two glass doors are pulled opposite each other, the glass sliding door does not usually move much).

This is most likely the murderer's hiding place. The murderer was standing behind the sliding glass door against the wall, which happened to be a dead end, and people standing outside could not see him.

Chen Qidi's clothes were intact, and Chen Jie and Liu Dayu laid Chen Qidi's body flat on the ground in front of the bathtub (Chen Qidi's body turned out to be curled up behind a glass sliding door, with his back to the wall and his head against the glass sliding door).

Chen Qidi's right foot was wearing a slipper in the shape of a white rabbit, and the other slipper was next to the flush toilet - directly opposite the wooden door, indicating that Chen Qidi was about to go to the toilet when he was killed. Of course, Chen Qidi's request to go to the toilet is not as eager as his sister Chen Qiming, Chen Qiming is wearing a pair of Li Ning brand sneakers on his feet, and the laces are tied well, it must be because of urgency, she did not change her slippers, and walked into the bathroom after throwing her schoolbag on the sofa.

On the right side of the security door, there is a coffee-colored shoe rack, and there are several pairs of cotton slippers on the shoe rack, one of which is a small slipper in the shape of a bear, this kind of slippers should be Chen Qiming's, and there are two pairs of women's cotton leather shoes on the shoe rack, one pair is red, with half high heels, which is more fashionable; A pair of black with a flat bottom. The red leather shoes are Ma Wenjing's, and the black leather shoes are Mr. Ma's. There is also a pair of Li Ning brand sneakers on the shoe rack, which Chen Hongxiang said are Chen Qidi. For children, the time to hold urine is relatively short, and when school is over, the toilet is overcrowded, should the sisters choose to go home to solve it, because home is near the school? Chen Hongxiang also confirmed Ouyang Ping and Liu Dayu's analysis that the two children do have such a habit, and the first thing they do when they get home is to go to the toilet.

Judging from the whole process of committing the crime, the murderer seems to know the situation and living habits of Mr. Ma's family well, and he chose the time when Mr. Ma was not at home, the only thing that is difficult to figure out is why he chose the time when his two children are about to leave school? This time is very easy to meet the Chen Qiming sisters. So, judging from this point, the murderer doesn't seem to know much about the situation of the two children.