The FBI seems to be indicating that something contained in these notes may have led to the murder of this individual, Ricky McCormick.
In other words, did Mr. McCormick know "too much"?
JMO: the emotions expressed in the forming of the characters suggest intense fear, tension, but not panic. He is describing a dangerous situation, but he is taking his time.
McCormick did not have steady meaningful employment. His formal education was minimal, but he is known as "street smart." He was perhaps a type who might blend in easily in a downtown location.
Could he have been earning extra cash working as a paid observer for a private investigator?
Let's imagine that he was being employed (maybe off the books) by an investigator to observe some building in St. Louis. Perhaps he was stationed in a higher floor of some other office building, across the street or at least proximate to the building he was observing. He may have also had some type of a listening device which accessed police channels.
These particular notes might record his observations of police response to some incident which occurred at the building.
The letter "E" may refer to the building or to the entrance to that building. "CBE" might mean "could be E." In other words, hearing the police report, he then guesses whether it might the E.
In some cases, "S" may refer to the building security. Since security could be a major focus of his attention, we might assume that this building houses sensitive operations.
The first page consists of 13 lines; the second of 18. Total lines: 31
Line 5: WLDRCBR~SG ~ T 06~ENTxSE . CR5LE . CTTRSe WLD~CBE
With listening device.
Receiving call by R.
Security Guard.
Total [cars] are 6. Entering by Service Entrance.
Cars responding: 5 are law enforcement.
CTT responding to scene.
With listening device.
Could be E.
Line 12 (TF ~?<MSP SOLE MR De LUSE TOTe WLD ~ WLD ~ CBE)
Totally *advertiser censored**ed. Missouri State Police, Security, other law enforcement (agencies) responding. Use L to T. [? Use elevator to top of building?] ... Could be E.
Line 31: D W m.y M16 xDRLx
Dead - White male young M16 rifle ...
Scenario?
Maybe McCormick picked up a message from the building security to the police that a body had been found with an M16 rifle. Or they had been forced to shoot an intruder who had been armed with an M16. Police then called other law enforcement agencies for back-up. They enter the building. Use elevator to go to the top of the building. Confirm that a man has been found dead.