Indirect questions should use special "indirect" Interrogative Words, but the Greeks often use the ordinary "direct" Interrogative Words instead.
To convert an ordinary Interrogative Word into an "indirect" Interrogative Word,
just add an omikron before it.

poqen  hlqeV;

"Where did you come from?"

hromhn poqen elqoiV.    OR (more correctly)  hromhn opoqen elqoiV.

"I asked where you had come from."
 

Note: tiV turns into ostiV.

tiV estin;

"Who is it?"

ouk egnwn tiV eih.    OR (more correctly)  ouk egnwn ostiV eih.

"I did not know who it was."