Our own review of FBI files pertaining to weapons acquisitions reveals sporadic information on the Colt Monitor. From documents found, it is clear that Colt salesmen "pitched" the Bureau on the Monitor in June, 1933. However, the files show that in all liklihood, purchase of the Monitor did not occur until 1934.
We've set forth a few documents here that may be of interest to readers:
The June, 1934 Monitor distribution list - it is believed this is the first distribution of the Monitor Bureau wide.
June, 1934 Monitor training memo - it is believed that this is the initial stages of training.
As of 2015, we're attempting to locate additional documentation regarding the Bureau's use of the Colt Monitor.