Talking to Trudy at least gave you a direction where to look for your attackers, so get out of Goodsprings and head south towards Primm. On the way, you will surely encounter Powder Gangers and some nasty beasts that the devastated lands have the secret, so stay on your guard until you arrive near the city (Image 1). There, an NCR soldier will tell you that Powder Gangers have just captured the city. Bad luck for you, the relay station is located in the zone controlled by the prisoners, you will have to enter by force. Go around the central road and go to the right to reach the bridge to Primm (Image 2). Pay close attention to the mines on the ground (shoot them to blow them up) and enter the town. On the other side, move forward gradually by getting rid of the few powder compacts that occupy the streets (Image 3).
When you are finally calm, enter the Vikki & Vance casino on the left (Picture 4). Inside, you will meet the local courier manager, a Mr. Nash. This will tell you that the only person likely to help you find your attackers is being held hostage by the Powder Gangers. Get out of the building and head this time towards the Lucky Casino located just opposite (Picture 5). Inside, you are free to play it discreet or on the contrary to blow up everything, in both cases, get rid of all the Compacts that patrol the corridors (Image 6).
In the large room at the back of the building, you will find the head of the Powder Gangers, you can of course eliminate him but know that he is equipped with a flamethrower (Picture 7). It's a good booty you say. Once quiet, enter the room to the left of the Great Hall to find Deputy Beagles (Picture 8). Untie the young man and take him out of the Lucky Casino. You will then learn from the deputy that the men responsible for your "death" left for Novac via Nipton.