Why was the casket filled with clothing and blankets in Number the Stars by Lois Lowry?

In "Number the Stars" by Lois Lowry, the casket was filled with clothing and blankets to make it appear as if it contained a dead body, so that the German soldiers would not inspect it closely. By disguising it in this way, Annemarie's family was able to transport important items to safety without arousing suspicion.