The mummy was excavated from a Roman cemetery in Hawara, Egypt in 1911, and is believed to date between 30 B.C. and A.D. 395 After its excavation, it was acquired by the Brooklyn Museum.
Demetrios was prepared in a way that is called "red shroud mummification". The surface of the linens was covered with red lead paint. There are less than a dozen of these so-called “red shroud mummies” known to exist in the world. The inscription on the shroud was in Greek rather than Egyptian hieroglyphics.
A portrait of the dead man was included in the wrappings covering his face.
CT scans and shroud markings determined his age at about 59. Gall stones were also found preserved in the gall bladder.
The cause of his death was unknown.
The mummy has never unwrapped in modern times.
Bleiberg, E. (2008). Who Was Demtrios and How old was he When he Died?. https://www.brooklynmuseum.org/community/blogosphere/2008/06/18/who-was-demetrius-and-how-old-was-he-when-he-died/