逃す

1. Origins, structure, and basic meaning

• Structure: 逃す(にがす) means to release or let escape someone or something held or within one's control.
• Basic usage: It covers both releasing an insect outside and allowing a captured person to escape.

2. Common pitfalls and similar expressions

• Intentional release and an unintended escape
  • In the first example, 外へ逃す is a choice to release the insect outside. In the second, 逃してしまった describes losing the thief while dozing, so the verb does not by itself imply an intentional act.