Not so.

The purpose of the above methods is nothing more than to achieve the purpose of disfiguring, interfering with dental identification, and eliminating fingerprints. These methods will only work in the past or when criminal investigation conditions are insufficient. If it is a big city with good medical conditions, it will basically be easy to identify the person through DNA testing based on the investigation results.

It should be noted that if the corpse is burned in a very thorough way like that in a crematorium, it can indeed completely erase all personal characteristics. However, since there is no proof of death without evidence, cremation is generally not as professional as cremation. I am afraid that the DNA information will still be preserved in the bone marrow and other locations. It's not a completely safe approach.