NCO

Yasuo Uchidaの "The Togakushi Legend Murders"（原題　戸隠伝説殺人事件） を読み始めました。
“Oho! You've been living quite a life here, I see!" said the officer, barging straight into the room, casting a lecherous look at Taki in her shrine-maiden's costume. "Well, you can't make fools of the army like that." He glanced back at the NCO behind him, then turned toward Tachibana and shouted, “Get up!”

"NCO" は警察官の身分・階級を示しているようですが、知らない略語なので辞書を見ます。

・Collins Dictionary: An NCO is a soldier who has a fairly low rank such as sergeant or corporal. NCO is an abbreviation for 'non-commissioned officer'.: Food for the ordinary Soviet troops and NCOs was very poor.
・Cambridge English Dictionary: abbreviation for non-commissioned officer: a member of the armed forces who has achieved the rank of officer by rising from the lower ranks rather than by receiving a commission

下の階級なので、日本の警察官で言うと巡査か巡査部長を指すと思われます。