Wow, that makes lots of sense. The FBI would have all that capability.
It also seems the General retired a year before one of the memos were typed.
They really have to see if those old typewriters could do that as a feature as well. LOL
...I believe the FBI is also capable of determining when, where and by whom a paper was made and how old that particular sheet of paper is, which businesses and government agencies ordered/used that type of paper, etc. I also believe they have vast resources permitting them to identify the properties of inks used in things like pens... and typewriter ribbons.