[1] He was born in New York City in September 1881 or 1882 to photographer Enrique Muller and his wife, Mary.

His father had worked in the post office in Kiel in Germany, and migrated to the United States and lived New York City.

Father, Enrique Muller and his two children, Robert and Theodore operated a photographic studio in New York City.

The Kaiser thanked the photographer, by sending him a pair of gold cufflinks.

[4] In 1912 he published Battleships of the U.S. Navy, and in 1913 Risks of Photographing Battle-Ships in Action.