a murder / a homicide

殺人事件<
※a を抜くと動詞になるので注意
homicideは専門用語で、警察や弁護士や医師が使う言葉

• Police: This death has been confirmed to be a homicide
• A regular person: This death was a murder

Reference source

• https://eikaiwa.dmm.com/uknow/questions/16449/