IPA: /ɪnˈdaɪktər/
KK: /ɪnˈdaɪktər/
A person who formally accuses someone of a crime, usually in a legal context.
The indictor presented the evidence to the grand jury.
Indictor is formed from "in-" (meaning not) and "dicere" (meaning to say or declare). The word refers to someone who declares or states something, often in a legal context, such as bringing charges against someone.
Think of someone 'declaring' ('dicere') something 'not' ('in-') — that's why an indictor is someone who states or brings forth charges.