L.A. Noire/Upon Reflection
The game begins with a voiced-over cutscene and you'll get a call on the patrol car's radio from KGPL asking you to respond to a detective's call at Sixth and Industrial Street. You'll be going on an evidence search with your partner, Ralph Dunn. After he responds that you're en route, you'll be in control at the wheel of the patrol car, and the objective will be marked on your minimap with a yellow flag. Follow the on-screen directions, which explain how to drive the car. The crime scene is nearby, just one right and one left until you're there.
 Alleyway Crime Scene
Detective Rose will give you your orders: find the gun that the perpetrator was seen throwing away somewhere in the alley. When the detectives leave, you'll be in control of Phelps and you can search through the alley. As you walk around, you'll receive more on-screen tips explaining how to investigate the crime scene for clues. Down at the end of the alley you'll find a door with a bloodstain on it and a pool of blood on the ground. Next to the blood, you'll be able to make another inspection and this time you'll see the weapon in the reflection of a window. Head around behind the building opposite the window and approach the yellow pipe to start climbing to the roof. Up on the roof you can walk over to the gun and pick it up for further inspection. Rotate the weapon clockwise (so your palm is facing up) and you'll read off the serial number. Investigate further and you'll see that two rounds were used before the assailant tossed the gun.
Head back down to your partner and you'll decide to do some research at a local gun shop. Make your way back to the patrol car and hit the road. When you get into the car, your notebook will open up automatically and you can set the gun store as your next destination so it's marked on your map.
 Gun Store
At the shop, walk into the door (gold handles mean you can open them) and enter the store. The proprietor will give you some info about the gun and you'll find out that he actually sold it. Since Smith & Wessons are special orders, you'll be able to look through his ledger for the owner. You can find the weapon by its description (Model 27 with pearl grips) or by the serial number you found at the crime scene (S71893). Either way, tap the fifth entry down on the second page to get the suspect's name and address to add him as a person of interest. With a new location you're ready to get back on the road and see if he's at home.
 Schroeder's Apartment
Head across the street and enter the apartment building, where you'll see from the mailboxes that Schroeder is in apartment 2. Head upstairs and approach the suspect's door to knock on it. When you get inside and try to arrest Schroeder, he'll put up a fight and you'll go toe to toe with him. Give him a beat down, then cuff him and take a look around the apartment. Over at the dresser drawer where he was looking for the gun, you'll find a green notebook with names and numbers in it, including the detective who originally called for you at the beginning of the case. You won't need to find out what those numbers were all about though—you'll take the commendation for breaking the case instead.