[1] Lohse, who published a scholarly thesis on painter Jacob Philipp Hackert in 1936, worked as an art dealer in Berlin from 1936 to 1939, selling paintings out of his father's home.

As the ERR's Deputy Director in Pari] from 1942 to 1944, Lohse helped supervise the systematic theft of at least 22,000 paintings and art objects in France, most of which were taken from Jewish families.

[6] Lohse was ordered by Robert Scholz to protect Nazi art holdings and records from destruction, and to "turn them over to the American authorities at such time as Füssen [a nearby town] might be occupied.

"[7] Facing a possible death sentence[8] for crimes witnessed in Paris by Rose Valland (and others), Lohse underwent a two-month interrogation,[9][10] during which he shared a cell with two other notorious Nazi art looters, Karl Haberstock and Walter Hofer.

[11] The suicide of Baron Kurt von Behr proved to be a godsend to Lohse, permitting him to blame the systematic confiscation of French art collections on his former ERR chief in Paris.

[13][22] According to the historian Jonathan Petropoulos, Lohse maintained contact with former Monuments Man Theodore Rousseau, a curator at the Metropolitan Museum of Art, exchanging letters and seeing him in New York and in Europe on multiple occasions.