German authorities announced on Friday that they had made progress in an investigation into possible falsified documents sold to the Dresden Bundeswehr Museum.

The public prosecutor and police said that at least 24 documents purportedly from Claus Schenk Graf von Stauffenberg — a military officer who was involved in a plot to assassinate Adolf Hitler — are "most probably" forgeries.

Investigators have been looking at the series of documents sold to the museum between 2015 and 2016 by a 51-year-old man for €14,900 ($15,818 at current rates).

What do we know about the investigations?

Police suspect that the man fabricated the documents himself, or knowingly had someone else do it, before presenting them to the museum as genuine.

A police search in the city of Neubrandenburg in Mecklenburg-Western Pomerania resulted in the seizure of numerous items of evidence including six typewriters, old ink, stamping ink, old paper, a laptop and mobile phone, and various storage devices.

The suspected counterfeit documents dealt with supposed written communication from Stauffenberg to other figures in the military, including other co-conspirators.

Authorities warned that they would still need a "considerable amount of time" to complete their investigation.

Who was von Stauffenberg?

Stauffenberg served in the Germany army as an officer under Hitler.

On July 20, 1944, he took part in a failed attempt to assassinate the Nazi leader with a bomb planted at the "Wolf's Lair" Nazi headquarters in East Prussia.

He was shot along with several other co-conspirators for his role in the plot.

The incident was used as the basis for the story in the Hollywood film "Valkyrie" in 2008.

Stauffenberg and his act of resistance serves as a central reference point for the present-day Bundeswehr's value system. The Bundeswehr holds a ceremony in his honor every year.

ab/nm (AFP, dpa)