I agree that there was an assassination attempt on Arandor. But it should be taken into account that no clues are given for unsuccessful assassinations, except for the one that was planted.
This means that the clue about the old Necropolis vehicles is planted!
Added 5 minutes later
1. You don't try to find clues on the cylinders anywhere.
4. You reacted to my post about the possibility that you are Mafia with immediate aggression, even though I hadn't stated that yet.
6. But it seems you haven't figured out who will be fabricating the clues with the companion, and you both drew them...