In ancient times, killing people was a very taboo thing. Although it was the execution of prisoners, they deserved it, but the ancients still attached great importance to those superstitious statements. The ancients believed that people died of yin qi, so they tried to prevent this situation when executing prisoners. This is also because in ancient China, Xi was originally its capital, and later it was changed to Beijing. However, according to the old custom, Xi 'an was chosen at the peak of the sun, that is, at 3 noon in Beijing. This is a completely superstitious statement. Just listen, there is no need to delve into it.
There is also a saying that three o'clock at noon is chosen to prevent unforgivable prisoners from becoming ghosts, and to dilute the yin of the dead with the most abundant yang. Another thing I think is to calm the psychological fears of the people and executioners. Just think, if you choose to ask questions at night, it is definitely a super scary thing, and choosing 3 noon is more acceptable and people are not so scared. The executioner can also get some psychological comfort, saying that the ghost of the deceased will not stay.
So there are many reasons for choosing three o'clock at noon, more out of superstition, but some of them are to eliminate the fear of executioners and onlookers.