Fascinating con tricks that apparently use a fraudster that can mimic voices (or, if the future is here: a computer voice changer, which would be cool)..
Not very sophisticated as far as cons go, they basically just impersonate someone important and vaguely known to the victim, then present a crisis situation and ask for money.
It is interesting that the one instance included an offer to meet the “secretary” of the alleged requester. The scenario “send someone to my office and have them speak with my secretary, with a passphrase to vouchsafe identity” is fairly common confidence game technique. The victim is simply met by someone in the public area of the official location. Not using the private office is explained away by, e.g. “on the way to a meeting, no time” or, “lets go to get lunch,” etc. etc.
Always, the important thing is to keep up the urgency so that the victim is rushed along without an opportunity to think and consider the events (and notice the holes or other change their mind.) It is quite effective. And still being done this day! The old ways of professional crime are not completely vanished…