Pseudonym: Knittel, Peter
A memo by Henry D. Hecksher, on the AMWORLD Meeting in New Orleans on June 24, 1964, mentioned that the following CIA officers were known to AMYUM-19 (Cesar Baro Esteva): Bobbie Hernandez, Raul Hernandez, Carl Jenkins, Karl Rohrer, Desmond FitzGerald, Henry Hecksher, Richard Beal, and James Smith. The memo added that AMYUM-19 knew Russel H. Sambora (P - Manuel Chavez) and Peter C. Knittel (P), and may suspect that they are somehow linked with the CIA.
In a memo by Henry Hecksher in May, 1964, he mentioned a Beckhoff (full pseudonym was James E. Beckhoff), whose real identity was the same as the author of the memo. Therefore, Hecksher already had previous form for mentioning other pseudonyms of his when writing a memo under his own name, and it is possible that the same happened when he mentioned Peter C. Knittel.
Larry Hancock, in Someone Would Have Talked, mentioned that Hecksher was referred to as "Peter" in fellow CIA officer's David Phillips' book, The Night Watch, citing journalist Joseph Trento in the process. Hecksher worked with Phillips during the operations in Guatemala against the democratically elected regime of Jacobo Arbenz Guzman.
Thus, it is possible that Henry Hecksher used the pseudonym of Peter C. Knittel in Guatemala and beyond, and that was the reason David Phillips referred to Hecksher as "Peter."
https://www.cia.gov/readingroom/docs/DOC_0000914854.pdf
07/29/53: Air dispatch from Chief, DTROBALO to Chief, WH: Subject: General - Operational. Specific - PBFORTUNE: "Transmitted herewith in triplicate is a memorandum of understanding, made as a result of our discussions with Lawrence F. Sillence. Richard F. Arville." - - - Pages 2-3: "Conference in Richard F. Arville's office on 24 July 1953, at which time the following were present: For Headquarters, Lawrence F. Sillence, Stephen O. Brigford, Peter C. Knittel and Kenneth T. Offen; for DTROBALO, Richard F. Arville and Jacob B. Hirschwood. Discussions Resulting in the Following Understandings were Reached: 1. Arville stated that nothing stated by him, or his deputy, or anyone representing DTROBALO, would be intended to alter, change or deviate any Headquarters' instructions in any degree. 2. Each of the gentlemen from Headquarters stated he had received certain instructions, and understood his assigned duties and instructions. 3. The date and hour of the departure of the (REDACTION) was agreed upon as 0600 hours 25 July 1953, depending upon any difficulty encountered. 4. The condition of the engines was brought up and Offen stated the ship would be ready to depart in so far as he is able to determine at this time...6. The total complement, officers and men, was discussed and the total placed at 16. The list of officers and men was read and approved. 7. Communications: It was understood that the same Chief Communicator would be used on the present trip as we used on the last trip, and that Louis B. Solliday would not be needed as Assistant Communicator..." Oliver G. Galbond (J.C. King) and Seekford were mentioned in point 13. (Reconnoiter).
104-10163-10041: ARTIME BUESA, MANUAL (VOL XII).
05/20/64: Memorandum from Henry D. Hecksher WH/SA/SO/HH: AMWORLD Meeting in Washington, D.C. 19 May 1964: Subject: AMBIDDY'S Personnel Policy: Page 2: ..."10. Beckhoff (Henry Hecksher) commented as follows: AMYUM-19 (Cesar Baro Esteva) will have to tell Guertler (probably Karl Rohrer) or myself if in a given instance a personnel demarche is indicated. There are certain things which, with AMBIDDY-1 (Manuel Artime Buesa) out of the country, simply cannot be put on the shelf. We have no choice but to tell Guertler to tell AMYUM-19 who, however, should feel free to counsel us not to use him as a channel. Headquarters rep conceded that AMBIDDY-1 could rightly resent anything which smacks of a junior officer (i.e. Guertler) giving orders to him via AMYUM-19, an impression we would do our best to eradicate."
104-10163-10041: ARTIME BUESA, MANUAL (VOL XII).
Memorandum from Henry D. Hecksher, WH/SA/SO/HH: AMWORLD Meeting in New Orleans, 24 June 1964: Subject: AMYUM-19 or Nice Guys Finish Last: Page 5: ..."a. Under assumed names, the following KUBARK (CIA) reps are known to him (note: refers to AMYUM-19 - Cesar Baro Esteva): Bobbie Hernandez, Raul Hernandez, Carl Jenkins, Karl Rohrer, Desmond FitzGerald, Henry Hecksher, Richard Beal, James Smith...c. He knows the following individuals and may suspect that they are somehow linked with KUBARK: Russel H. Sambora (P), Peter C. Knittel (P)..."
Larry Hancock, Someone Would Have Talked (2010)
Page 110: ..."Success in Guatemala: It appears that Henry Hecksher was called in as the lead field officer inside Guatemala. He took Phillips into the country for intelligence work and may well have been the officer who brought Morales into the project from the Berlin station, referred to inside the CIA as Berlin Operating Base or 'BOB.' Hecksher is referred to as 'Peter' in Phillips' book, The Night Watch, according to Joseph Trento (12)..."