Cryptonym: MPCHEEK
https://www.archives.gov/files/iwg/declassified-records/rg-263-cia-records/second-release-lexicon.pdf
CIA Soviet Division (at p. 49 of this document).
104-10187-10009: CIA FILE (ASSET) PHOTO SURVEILLANCE OP.
01/13/73: Cable to Director (Rostedt Acting): Slugline RYBAT REDLEG KDFACTOR: ..."3. Married couple originally vetted by us and held in reserve for this photo operation (subjects of Ref C) were, as you know, diverted last week to occupy LP for MPCHEEK audio operation. 4. We have not yet asked subject Ref A and wife if they able and willing run photopoint for us, but Oliver J. Mankunas who knows their personal and financial condition believes they would welcome opportunity..."
104-10225-10006:OP FILE ON DANIEL FLORES
06/28/73: Fitness Report for Daniel Flores: Reporting Period: 1 July 1972 - 31 May 73: ..."SPECIFIC DUTIES: SPECIFIC DUTY NO. 1: Station officer responsible for operations against the MPCHEEK target. RATING LETTER: S (note: Strong)...SECTION C: NARRATIVE COMMENTS: Following realignment of Station officer assignments last year, Subject was given the responsibility for operations against the MPCHEEK 'hard target'. He also assumed additional tasks in more traditional areas...Particularly against the difficult MPCHEEK target, this officer has displayed admirable determination despite the inherent frustrations and disappointments of working against this remote and suspicious group. During the period under review, his job has been the more difficult since the MPCHEEKS, in all probability (REDACTION) Station (REDACTION) (in which Subject played a major role), have withdrawn into a defensive shell which makes access operations verge on the impossible. Nevertheless, he has continued to probe their defenses, and has managed to develop (REDACTION) leads which, with the exercise of patience and application of his proven operational resources, could eventually (REDACTION) to the (REDACTION) MPCHEEK Mission here. This officer refuses to become discouraged, a quality officers working on hard targets must have..."
104-10225-10006:OP FILE ON DANIEL FLORES
03/04/74: Fitness Report for Daniel Flores: Reporting Period: 31 May 73 - 4 March 74: ..."SPECIFIC DUTIES: SPECIFIC DUTY NO. 1: Station officer responsible for operations against the MPCHEEK target. RATING LETTER: S (note: Strong)..."