When added to the word detect, which suffix means "a person who"? - ive - ary - tion'

When added to the word detect, the suffix which means "a person who" is - ive.

"A person who" means that you need to create a noun which refers to a person by adding that suffix. If you add - ive to detect, you will get the noun detective, which is obviously a person.

The word detectary doesn't exist, and the word detection doesn't refer to a person, but rather the act of detecting.