Arson on ships is not a new thing and in the past NCIS Agents were given excellent training re investigating such events and the Navy put a very high emphasis upon the importance of solving those cases.
The ATF also are very good at those kinds of investigations.
The Forensic Evidence in a fire of this magnitude and intensity shall be very hard to secure.
As Nutty notes the human side of the investigation probably shall provide the most useful information.
Reportedly, there were less. than two hundred Sailors aboard the Ship as it was undergoing repair and modifications in the Yard thus the majority of the people aboard the Ship were civilian yard workers.
Identifying possible suspects would require quite a bit of gardening to develop information that might offer some insight into a motive and also show opportunity once the general area of the origin of the fire was determined.
Those not involved but aboard the ship could upon being interviewed would surface some names and Watch Assignments would identify yet more names....and after that it is just eliminating possible suspects till you have but a few to carefully consider.
I am curious as to what information was found that revealed it was a case of Arson and not an accidental fire.