Suspected Synth

 is a quest in Fallout 4.

Location
The same quest may occur at other settlements.

Tenpines Bluff (Confirmed)

Quick walkthrough
When returning to Outpost Zimonja after establishing the location for the Minutemen, you will come come upon a settler brandishing a weapon at another individual. The first settler is accusing the other of being a synth. It is up to you to decide of what to do with the person accused.

Detailed walkthrough
Walking in from the wasteland, you can hear yelling and other signs commotion coming from the outpost. There in the middle of the compound, a settler is aiming a pipe pistol at another settler saying that she has been watching this one for some time and is ready to kill the synth.

The accused settler says that she is not a synth. So, it is up to you to decide on whether or not to kill the settler.

In talking to the accused, you will have a "Interrogate" option [ orange speech check ], kill the settler, let her go, or let the person accusing to decide.

On a successful interrogation, the accused will admit to being a synth. Also, the let her go option changes to where you have to lie and say that they are not a synth.

So, it is up to you on whether to let the synth live or die. By choosing either the "kill her/him" option or "your call" options, the accused synth dies. Otherwise with a "let her/him go" or the lie, the synth will live.

With this quest, it does not provide information yet of whether the synth is hostile or not.