To unlock Hardboiled mode, beat the game on Detective mode.
To unlock Dead On Arrival mode, beat the game on hardboiled mode.
To view the second ending, beat the game on Dead On Arrival mode.
In Chapter 7 continued of Part 1, after you kill Kaufman and his henchmen at the end of the level, go back into the vacant apartment you went through to reach the lobby where you fought Kaufman. In the apartment, you should find a home-theatre system. Turn on the flat screen TV. You will see a short video.
Kill the two guys on the window cleaners lift head down a usual. After the cleaner shoots the guy in the suit out of the window kill him and head left on the balcony, jump through the opening in the scaffolding, and continue to head right until you see an open window. Go through and you'll find the shrine.