At La Esmeralda, he focused on this kind of painting, being influenced by the work of José Clemente Orozco, Rico Lebrun and Leonard Baskin. In 1950 he traveled to various parts of Mexico, especially the Isthmus of Tehuantepec. From this trip, he wrote a script for a radio documentary on the region's music, customs and legends, produced by Canadian Broadcasting Corporation. In the same year, he met David Alfaro Siqueiros, forming both a personal and professional relationship. He was an assistant on two murals from that time "Patricios y Patricidas" at the former customs building in Santo Domingo along with the "Cuauhtémoc" mural at the Palacio de Bellas Artes from 1950 to 1951. The experience not only influence his style but also taught him the level of quality expected in Mexican muralism. In the early 1950s he joined the Taller de Ensayo de Materiales y Plásticos run by Prof. José L. Gutíerrez at the Instituto Politecnico Nacional, participating in the creation of various collective murals. From 1954 to 1956, he studied engraving in metal with Lola Cueto at Mexico City College and lithography from the Escuela de Artes del Libro with Pedro Castelar Baez. He also participated in the workshop of Guillermo Silva Santamaría where he met Francisco Icaza and Leonel Góngora. Beltran spent most of the rest of his life in Mexico, except for a trip to Europe and a number of years spent in New York City in the 1970s, connecting with American painters such as Omar Rayo, Rudolph Abularach, César Paternosto and Rubens Gerchman . For Expo 67 in Montreal, he represented Mexico rather than Canada. He returned to Mexico to stay in 1976, becoming a naturalized citizen in 1981. He was married once, to dancer Esperanza Gómez with whom he had two daughters. After they divorced, he had numerous relationships but did not remarry or have more children. At the time of his death, his partner was Patricia Quijano, and he had one grandchild. Belkin died in Mexico City on July 3, 1992 from lung cancer at age 61. He was buried at the Panteón Judio in Mexico City with honors. Belkin's career spanned more than three decades, during which time he produced 28 major public murals, various smaller ones, with about ninety individual exhibitions and over fifty collective ones in Mexico and abroad and designed sets and costumes for forty Mexican stage productions, as well as other activities.