why do journalists and authors often put brackets around words in seemingly strange parts of sentences?

Question

For example, a sentence I just read went as follows:

> “‘I don’t think [the book] had anything to do with his arrest and neither does Anne Marie Schubert,’ he says.”—(Excerpt from the appendix of ‘I’ll Be Gone in the Dark’ by Michelle McNamara)

Found in Other.

Answer 1

It’s for clarification within the quote, to spell out what person was talking about… person actually probably said “it” but “the book” was swapped for clarity.