On this page of our guide to Wolfenstein: Youngblood you will find a detailed description of Infiltrator's Report side mission. This task concerns the location of the title report of the murdered member of the resistance. That means a visit to the Brother 1 district.
Who's commissioning the mission: Talk to Jemma Atwood in the hideout in the catacombs.
This task takes place in Brother 1 district where you could have unlocked a fast travel point (subway) - see separate pages of our guide for more information. When you reach this district, set the mission as active and follow the instructions on the mini-map.
You have to break into the prison. If you have used the shortcut before, then after you reach the Gestapo building from the above picture you can choose any side staircase and immediately get inside. Otherwise you have to choose a roundabout way to prison. In both cases, it is necessary to use the elevator that goes to the prison.
Once you find yourself in prison you can engage in fights with Nazis or remain in stealth mode. The goal of the trip is shown in picture 1 with sliding cabinets - they contain materials and precious evidence. Check the second rack from the left - you will find the Infiltrator's Report (picture 2). Exit the prison using fast travel option or return to the eleveator. The report should be returned to Jemma.
Rewards: 12300 XP, 615 silver coins, 1 skill point.