A man is found murdered in his bathroom naked with blood scattered all around him. The bathroom was locked from inside and there is no trace of any struggle. There is nothing in the bathroom except his pant with the belt still around and his shirt. Also, the medic team can't find any incision in his body that may have been the reason behind so much of blood loss.

The Police department is clueless regarding this murder mystery. But Sherlock solve the case.
Can you ?

Spoiler Alert Inspired by Sherlock Holmes Season 3 Episode 2 (The Sign of Three)

Sherlock Holmes The Sign of Three Logic

The killer did not need to be present at the crime scene. He used sort of an artistic technique to kill the victim. The incision was made by the very fine and this incision blade which is barely visible to naked eyes. It was stuck in victim's belt at any random point of time and he did not feel much due to the extremely fine surface of the blade. When the man undressed, he had to remove his pants due to which the incision blade was removed from his body cutting finely in its way out.
In this manner, the victim dies with the extreme blood loss and there was no evidence left.