にする in this sentence?


A character asked her what she was doing "here", and she answered :

> 捜査中に誰かを1人にするのは、極力避けようって話だったでしょ？

I don't understand the part with にする, what does that mean ?




「[1人]{ひとり}にする」 here means "to leave someone alone".

It should be remembered as a set phrase, but if you need to understand it
grammatically, 「～～する」 here means "to make/let/leave one ~~".

> 「捜査中{そうさちゅう}に誰{だれ}かを1人にするのは、極力{きょくりょく}[避]{さ}けようって話{はなし}だったでしょ？」

thus means:

> "We all agreed to do our best not to leave a person alone during the
> investigation, didn't we?"

