Pseudonym: Aparicio, Luis
Memo by C/WHD William Broe: "Mr. Flores has been working in WH/COG and its predecessor groups since 1963. His fitness reports have been consistently good and the comments of his supervisors laudatory...In WH/COG Mr. Flores has served as an Intelligence Assistant in support of CI operations. In addition he has assisted in the training of agents in REDACTED communications. Mr. Flores is bi-lingual - Spanish and English - and is adept as an operational Translator-Interpreter."
1978 Appendix 3 to HSCA Procedural Write-Up to Mexico City Trip 2: "HSCA staffers Edwin Juan Lopez and Harold Leap traveled to Mexico City on 8/7/78. The staff members were met by David T. Patton at the Mexican airport at 10:15 pm. Mr. Patton then checked the staffers into Room 1754 at the Maria Isabel Hotel...Steinfeld, CIA Chief of Station in Mexico City, wished to see us at 8:30 am the following day. On Tuesday, August 8, 1978, Committee staffers met with Larry Sternfield. He informed the staffers that the two individuals that the Committee wished to interview, Daniel Flores aka Luis Aparicio and Ramon Alvarez Durant (Note: aka LIEMPTY-1), were now available. At 9:30 am, 8/8/78, Committee members interviewed Danny Flores. (See write-up of Danny Flores interview). The interview ended at approximately 10:15 am...Mr. Steinfeld stated that the HSCA's interview with Ramon Alvarez Durant was considered 'highly sensitive'. He explained that three rooms at a nearby hotel would be used. In one room Ramon Alvarez Durant would sit, Committee staff members would sit in a second room, and two CIA personnel officers would insure that the equipment worked properly in a third room. Mr. Steinfield then telephoned Mr. Niles Gooding, who had been sent to the Mexico City Station from Headquarters to arrange the procedures for the interviews."
Another version of the above document.
Bill Simpich, State Secret, Chapter 6: https://www.maryferrell.org/pages/State_Secret_Chapter6.html
It looks like (Cuban embassy cultural attache Raul) Aparicio may have had some kind of relationship with Spanish-speaking CIA agent Daniel Flores. His stepmother was born in Mexico. Flores was approved to work on a special project by a CIA sigint (signals intelligence) officer. A sigint matter would indicate that Flores was working with Staff D. When HSCA counsel Ed Lopez went to Mexico City in 1978, he conducted an interview with “Daniel Flores aka Luis Aparicio”. Many baseball fans will remember the famous Chicago White Sox shortstop Luis Aparicio during the 1960s. Lopez asked Duran during her interview if she saw “Luis Aparicio” at a twist party in Mexico City. Was “Luis Aparicio” a momentary lapse by Lopez, did “Luis” have a relationship with Raul Aparicio, or did the CIA have a real live CIA officer inside the Cuban embassy? I have the feeling that this won’t take too much longer to figure out.
ARRB pseudonym decoder mentions that "Dan Flores a/k/a Luis Aparicio".