A cache of documents from Deutsche Bank AG include what a group of silver investors claim is a “smoking gun”: private electronic chats showing traders from numerous banks conspiring to rig prices from 2007 to 2013, according to a court filing in New York last week.

The bank provided the documents to the investors after settling a lawsuit accusing it of rigging markets in precious-metals. As part of the accord in April, the bank paid $38 million and turned over more than 350,000 pages of documents and 75 audio tapes. The investors now want to use the chats to win permission from a judge to file a new complaint against other banks.