SB 3.30.20

yātanā-deha āvṛtya
 pāśair baddhvā gale balāt
nayato dīrgham adhvānaṁ
 daṇḍyaṁ rāja-bhaṭā yathā
Word for word: 
yātanā — for punishment; dehe — his body; āvṛtya — covering; pāśaiḥ — with ropes; baddhvā — binding; gale — by the neck; balāt — by force; nayataḥ — they lead; dīrgham — long; adhvānam — distance; daṇḍyam — a criminal; rāja-bhaṭāḥ — the king’s soldiers; yathā — as.
Translation: 
As a criminal is arrested for punishment by the constables of the state, a person engaged in criminal sense gratification is similarly arrested by the Yamadūtas, who bind him by the neck with strong rope and cover his subtle body so that he may undergo severe punishment.
Purport: 

Every living entity is covered by a subtle and gross body. The subtle body is the covering of mind, ego, intelligence and consciousness. It is said in the scriptures that the constables of Yamarāja cover the subtle body of the culprit and take him to the abode of Yamarāja to be punished in a way that he is able to tolerate. He does not die from this punishment because if he died, then who would suffer the punishment? It is not the business of the constables of Yamarāja to put one to death. In fact, it is not possible to kill a living entity because factually he is eternal; he simply has to suffer the consequences of his activities of sense gratification.

The process of punishment is explained in the Caitanya-caritāmṛta. Formerly the king’s men would take a criminal in a boat in the middle of the river. They would dunk him by grasping a bunch of his hair and thrusting him completely underwater, and when he was almost suffocated, the king’s constables would take him out of the water and allow him to breathe for some time, and then they would again dunk him in the water to suffocate. This sort of punishment is inflicted upon the forgotten soul by Yamarāja, as will be described in the following verses.