In the chapter entitled Jericho of Detroit: Become Human, you'll have to track down 7 graffiti drawn in seven different positions to advance the story. It's a mandatory task, if you don't track them you won't be able to move forward. This procedure will guide you from one graffiti to another describing the most immediate route to reach them.
Before you start, remember that you can check what the next graffiti looks like by holding down L2 and you can scan the graffiti with R2 (you need to be close enough to them to do so).
Detroit: Become Human - Graffiti Location
Graffiti # 1 - Train Station
After getting off the train, turn left immediately. There on a red wall you will find the first graffiti. It's one of the easiest to find. At this point, you need to look at the graffito (face the front) and press R2 to scan. There are 2 small "X" symbols on it that you have to scan by holding down "triangle". This you will have to do for all the Graffiti.
Graffiti # 2 - After the escalators
Leave the train station through the escalators. After the escalators, the Graffito is right in front of you, it looks like a picture of a lion with a boxer.
Graffiti #3 - Building Beyond the Street
Since the last graffiti found (the lion's and boxer's graffiti), there are two pedestrian crosswalks in front of you. Cross the street and you will see a building with a lot of graffiti Behind the fence
Go further down the street, follow the left sidewalk. At the end of the sidewalk there is a fence on the left side. If you look through the fence you can see the graffiti. The two X-shaped icons can be scanned by standing in front of the fence. However, the third one is obscured by a wooden board leaning against the wall. To remove it you have to crawl under the fence (press L1 next to it). Remember that to get the button prompt that will allow you to remove the board, you must first scan the two icons visible on the graffiti. After passing the fence, remove the wooden board and stand in front of the wall. Now the last clue can be scanned.
Graffit # 5 - Dump
You must continue to follow the area behind the fence. There is a landfill with a big graffiti on the left wall. From the ground you can only analyze a clue. Two more clues are out of range. To reach them, you have to go up to the roof next to the graffiti. Pull the container near the wall and climb up. Then scan the two icons from the roof (note: one is almost invisible because it is a white "X" on a white background (not the eye of the person depicted on the graffiti.
Graffiti # 6 - Through the roof
Continue through the roof and jump the wall over the cliff. Once you get down on the other side, check the tall building that has red graffiti on it. It looks more like an advertisement than a graffiti, it can be easy to overlook at first for that very reason.
Graffiti #7 - Upstairs of the abandoned house
From the last graffito, you have to go up the building. To do this, follow the climbing path (you have to stay on the far left and then jump on the ladder). Once you reach the top, you have to align a pillar with part of the wall to get an "X" shaped graffiti. Part of the graffiti is on the pillar and part of it on the wall, so you need to find the right angle. It's a game of perspective.
And these are all the graffiti you can find in the Detroit Jericho chapter: Become Human. Now you can advance through the story to find Jericho, a secret hideout of the androids.