If you choose to leave the scientist alive then you can return to Kells and deceive him into believing that you have already killed him. You can choose to either kill the scientist or let him hide in a remote underground location.Once you are done talking with Kells, he will offer you another mission, wherein you are assigned the task of exterminating the scientist named Virgil who has helped you in various missions at the glowing sea.Then you need to assure him that the issue has been taken care of and the culprit has been persuaded to stop stealing the supplies. You can then return to Captain Kells and report the entire incident to him.Once you persuade him to accept the mistake, he will reveal the truth in front of you. Basically, just follow the target to his underground bunker and confront him.First of those missions is called 'Duty or Dishonour', wherein you need to follow a Brotherhood Knight initiate who is accused of stealing food and other supplies for the Ghouls and hiding them in the underground bunkers. Just go and talk to Captain Kells who will give you a couple of missions to accomplish.Here is how you unlock this powerful armour suit: Ross confirms that the suit can be unlocked 100% if you are playing as the Sentinel in Fallout 4. Visionary’s Helm legendary power armour location guide MrBossFTW via YouTube