Learn Turkish: Kimse cinayeti gizlememiş. - Apparently no one hid the murder.

The verb root is gizle- (to hide). First, we add the negative suffix -me to get "not hide". Finally, we add the reported past suffix -miş, which gives the meaning "apparently" or "I heard that". Together, gizlememiş means "apparently did not hide".

The translation says "no one," but the verb gizlememiş is negative. Does Turkish use double negatives?

Yes! The pronoun kimse means "anyone" or "nobody". When you use kimse as the subject to mean "nobody", Turkish grammar requires the verb to be negative as well. So literally, the sentence says "Anybody did not hide the murder."

Why is there an -i at the end of cinayeti?

The base word is cinayet (murder). Because it is the specific thing being hidden, it acts as a definite direct object and gets the accusative case suffix -i. This is why it translates to "the murder" rather than just "a murder".

Why does the reported past tense suffix take the form -miş here instead of -mış?

Because of vowel harmony. The suffix attaches directly to the negative suffix -me. Since the last vowel in the word is now e, the four-way vowel harmony rule dictates that the following suffix must use an i.