Murder
Murderer
When you kill a person that's murder.
ひとごろし
The readings are the kun'yomi vocab readings. So, if you know 人's reading as a vocab word and 殺す's reading, you should be able to read this word. Just note that ころし goes to ごろし due to rendaku.
人殺しをしたら、刑務所に行かなければなりません。
If you commit murder, you must go to prison.
昨日、この近所で人殺しがあったそうです。
I heard there was a murder in this neighborhood yesterday.
計算ずくの人生なんてつまらないと思って好き勝手していたら、いつの間にか人殺しになってたんだ。
I thought it wouldn't be fun to lead a calculating life, so I'd just do whatever I please, but I ended up becoming a murderer before I knew it.