The clue to Nefela's murder points to either Drakkosha or Wulfgar. There's a composer named Jeremy Soul; he wrote the soundtracks for the Elder Scrolls game series. Now, let's look at the suspects' signatures, which indicate Skyrim and Morrowind, respectively.
Belogorye
Небо – угроз не слышит
Небо – ведёт особый счёт
Небо – тебя найдёт