Per APF from MFriedel:
Mark began a career as an artist in 1966, studying painting at the Werkkunstschule in Wiesbaden, Germany under the mentorship of Oskar Kolb. He also taught himself the basics of photography and darkroom techniques with an older twin lens reflex camera. In the early 1970s, Mark was drafted into the United States Air Force and spent four years as a Still Camera Specialist and Lab Tech at Lowry Air Force Base Denver, launching his career in photography. After his Air Force tour, Mark was hired by the Denver Catholic Register as Staff Photographer. He also provided news coverage for NC News service in Washington, DC, the Christian Science Monitor and worked with the Denver Center for the Performing Arts as an event photographer.
He received two Colorado Press Association Awards and one from the International Photographic Society in Washington, DC. Until 2014, Mark was the staff photographer at the Central City Opera.
During the 1970s and 1980s, he also took an interest in street photography, particularly in photographing the homeless men and women who lived under the 16th Street viaduct in Denver.