L.A. Noire – Upon Reflection

Crime Scene
Head on back with your partner to the back wall to investigate what he'll find there. Head to the left of the door and inspect the area close to the door. You will find a clue sitting high up. Head to the right and around the building to find a way up to the rooftop. Walk right up to the drainpipe and you will automatically start climbing it. Just head on up and grab the evidence. Head over t othe left to collect that weapon. Give it a thorough inspection, looking it over, finding out the make, the rounds expended. Cole will keep the weapon and it's time to head back down the pipe and talk with your partner. He suggest just taking it back to Central, but Cole suggests checking in with the local gun shop to see if they might know something as he considers it something of a fancy piece.

Do as the game suggest, going into your notebook and setting the Gun Shop as your destination. Pretty simple to drive there. Take Mateo up to 6th, turn left, make a right on Central then a left on 4th and you're there.

Central Guns
Drive close to the store and you'll automatically get out. Walk up to the door and head on in. You almost immediately learn that the gun is available only from special order. Remember, the gun's serial number of S71893, it's a model 27 with pearl grips. Errol Schreoder is the owner of the gun. You'll find his name on the second page of the ledger the shop keeper shows you. You find address no problem. Time to drive on over there and investigate things a bit.

Again, use the notebook to set your destination. You'll want to head up Central, make the first right on 3rd, merge onto 4th place, which becomes 4th ave. then keep on that until you reach your destination.

Schroeder's Apartment
Again, when close you'll automatically get out of the car. Head across the street to get to the Apartment, you'll see the door on the left. You'll be prompted to look at the mailboxes to find out which apartment Schroeder is in. Phelps will look at the stair well, hinting for you to head on up to the next level and,,  likely, apartment. 2 is the first door on the left, so walk over to it and Cole will knock on the door. Errol will start talking with you quickly pointing out that Scooter works for Mr. Schroeder. He will invite you in at least so you can start working on this angle as he claims the gun is sitting in his drawer. He opens the drawer, is surprised to find that the gun is gone and Phelps quickly states that he is arresting him for the murder of Scooter. Errol lays out your partner so you need to win a fist fight against this guy. Take the advice given to learn how to brawl quickly, but Errol will give you plenty of time to learn the ropes. When prompted, press the grapple button twice to grab him then headbutt him down.

Head over to the drawer that Errol opened and investigate it to find a little black book. Your partnera  will finally get you to call in the case.

After that, you are treated to a flashback of Cole's during his military time.