The article presents documents from archival fonds of the State Archive of the Orenburg Region that narrate little-known facts of the biography of Alexander Gustavovich Dreyer, head of the Orenburg police and public figure, whose life was closely intertwined with the fate of Imperial family offspring Nikolai Konstantinovich Romanov. The significance of the matter lies in the opportunity to make known to contemporaries the outstanding personality of the Orenburg Polizeimeister through a variety of situations - not only in the service, but in the everyday life as well. Alexander Dreyer made a significant contribution to the development of Orenburg and the Orenburg region. A competent, energetic, and non-partisan man, he was actively involved in the creation of the city branch of the Red Cross, the St. Olga orphanage, in the improvement of the boulevard on the bank of the Ural and in many other beneficial activities. In 1877 Grand Duke Nikolai Konstantinovich, the grandson of Nicholas I, was placed under the secret surveillance of the Orenburg police. He fell in love with Alexander Dreyer’s daughter Nadezhda and wed her secretly. In their article the authors attempt to cover the main periods in the life of A.G. Dreyer. Particular attention is paid to the period of 1878-1881, which was a hard time for the family. The documents of the Orenburg gubernia administration, the Orenburg city board (uprava), the Orenburg gendarmerie administration, the office of the Bishop of Orenburg and Ural, and the Orenburg assembly of the nobility from the State Archive of the Orenburg Region, that are presented in the article, have not previously been published. To recreate Dreyer’s biography, two formulary lists (for 1872 and 1878) were used, as well as documents on entering retired Major-General A.G. Dreyer into the genealogical book of the Orenburg gubernia noblity for 1888. In addition to the documents, Orenburg periodicals were studied. Obituaries published after the death of A.G. Dreier, indicate that the inhabitants of the steppe region were sincerely grieved and tried to honor his memory with kind words. In this case, the obituary, being a historical source, provides the researchers with valuable information. A.G. Dreyer's autographs were also discovered; they are dated 1875. Unfortunately, it was impossible to find photographs of A.G. Dreyer.