Part of these documents of the 40s and 50s could be described as rather generic analytical reports, while some were reports by secret agents or retold such reports.
What follows is a June 12, 1952 Information Report--as all the CIA/'Forest brother' reports on LSM, it was retrieved by the Russian-language service--that stands out within the cache.
While the when, where and how of the way the CIA received the letter has been censored out, it seems that this "letter from the forest" was initially addressed to Latvian emigre organizations in the West. The letter from the report dated describes the situation in the Latvian resistance, outlines its most important developments and requests assistance in the form of money and weapons.
It is in English but it can be presumed that it was originally written in Latvian.
Click the image below to read it in full.