Learn Polish: Jakiś detektyw pyta, kto to zrobił. - Some detective is asking who did it.

Jakiś acts like an adjective meaning "some" or "some kind of" and always attaches to a noun, like detektyw in this sentence. Ktoś means "someone" and stands completely on its own as a noun. Saying ktoś detektyw would literally mean "someone detective," which sounds just as strange in Polish as it does in English.

Does jakiś change its ending like an adjective?

Yes! Because it describes detektyw (a masculine noun acting as the subject), it takes the masculine nominative form jakiś. If it were a feminine noun, it would be jakaś, and if it were the object of the sentence, the ending would change to match the case (like jakiegoś).

Why does the second part of the sentence use the masculine past tense zrobił if the detective doesn't know who did it?

The question word kto (who) always pairs with the masculine singular form of verbs in the past tense. Even if the detective suspects the culprit might be a woman or a group of people, the grammar rule dictates using zrobił right after kto.

Why is to placed before the verb (zrobił) instead of after it?