German historians have started compiling a central register of 9,000 mentally ill people murdered as part of the Nazis' euthanasia policy, most of whom were previously unidentified.
More than 100,000 people are believed to have been killed during a drive inspired by Hitler that was carried out in six extermination centres in Germany between 1940 and 1945.
The idea of a Nazi euthanasia campaign, backed by propaganda films portraying the mentally handicapped and incurably ill as "useless mouths to feed", was first outlined in Hitler's 1924 book "Mein Kampf" and became known as Operation T4.
Berlin's Freie University and the state of Brandenburg's memorial trust, located in Brandenburg town, are undertaking the one year project -- financed by the German lottery fund -- because they believe the issue has so far failed to receive the attention it deserves.
"We have wanted to do this for years, but the state archives and many of the necessary information sources only became available after German re-unification," said Guenter Morsch, a researcher at the Brandenburg memorial trust, on Thursday.
Today considered to be the precursor of the Holocaust, Operation T4 is believed to have claimed 70,000 victims between January 1940 and August 1941 alone.
Compiling the register is a vital part of Germany's efforts to shed light on its Nazi past, Morsch said.
"Firstly, it's a dignified way to remember the deceased, secondly, it's a service to the families left behind, thirdly it's important for general historical research, and fourthly it will serve an educational purpose," he added.
Horst Seferens, a spokesman for the trust, said most of the names of the people killed in the other five locations were known, in contrast to those who died in the town of Brandenburg.
Morsch said it was a little known fact that the first Jews to be killed were the mentally ill Jews in Brandenburg.
"Too few people are aware of how significant this town was during the Jewish Holocaust," he said.