At the end of the war, Gärtner was terrified at the thought of being repatriated to his hometown, which at the time became a part of communist Poland, and decided to escape.

Having studied English as an officer candidate, he perfected his command of the language, created a new identity as Dennis F. Whiles, obtained a Social Security card in that name, and invented a biography in which he had been raised in an orphanage after his parents had been killed in a traffic accident.

He eventually settled in Norden, California, where he worked as a ski instructor in the winter and in construction and sales jobs during the summer.

According to his autobiography, he joined a ski expedition formed to rescue the City of San Francisco, a train stranded in a blizzard in the Sierra Nevada in January 1952, immediately after which Life magazine took his and the group's picture.

However, since the authorities correctly surmised his reason for escaping, to avoid repatriation rather than a violent goal such as seeking revenge for Germany's defeat, he was not designated "dangerous", which would have resulted in a more intense manhunt.

[2] Upon his arrival by train in San Pedro, California as a fugitive, Gärtner first worked in various transient jobs as a dishwasher, cook, and laborer under the guise of a Norwegian immigrant named Peter Petersen.

For a time, he lived and traveled with a migrant farm family from Arkansas; the father's name was Dennis Whiles.

He also began working as a ski instructor at the Sugar Bowl in Tahoe during the winters, and as a tennis pro in the East Bay area.

He had not really escaped from prison since all German POWs were to be repatriated to their original homes, and Gärtner was due to be sent back to his hometown in Silesia, which had become a part of Poland.

In his later years he spent his time pursuing his passion as a painter and befriended other German-speaking locals, often hosting them at the bungalow he cohabited with an elderly German lady named Mildred.