Administration de la Sûreté Publique. Service de la Police des Étrangers. Dossiers individuels ouverts entre 1835 et 1912 (nos 1 – 999.999).)

The Foreign Police opened an individual file on each foreigner who entered the country. The files are numbered in the order assigned to them when they were first opened. These files generally consisted of: a declaration of registration in a municipality, references to the family and professional situation and the period during which the foreigner wished to remain in Belgium; relocations and changes of residence; civil status records, including marriage, birth and death certificates; the files dating back to the 19th century contain few photos except for the files of so-called "dangerous" foreigners; finally, the cover page of the file refers to the family names, first names and file numbers of close associates and family members of the person concerned. Although foreigners active in politics were in the minority, the size of their files is inversely proportional to their number – these are very rich – and include renowned personalities, such as Karl Marx or Victor Hugo. A file was closed after the foreigner's death in Belgium, voluntary departure or expulsion. These files were kept in a piecemeal fashion. Many files of foreigners in transit or staying for a short time in the kingdom were destroyed. The Public Security Administration preferred to keep the files that could be used to document case law and its legal expertise. To fill these gaps, the researcher should refer to the files of foreigners kept in the archives of cities and municipalities, particularly in Brussels and Antwerp.