A partner in the London office of U.S. firm Duane Morris is leaving the firm unexpectedly.

Three people with knowledge of the matter told Legal Week that disputes partner Jonathan Cohen has been let go by the firm, though he is still listed on the firm's website.

Duane Morris has not offered an explanation and cited a policy about not "commenting on individual personnel matters".

Cohen spent 18 years at Duane Morris, having joined the firm in 2001, according to the firm's website. One person with knowledge of the firm said he was considered one of the London base's senior litigators.

Having trained at Herbert Smith Freehills in London in the early 90s, before joining the U.S. firm he had stints as a litigator at Bird & Bird and legacy firms Barlow Lyde & Gilbert – now a part of Clyde & Co – and Winward Fearon & Co, which was incorporated into Mills & Reeve two years ago.

He has acted on a string of big-money cases, including representing Metric Capital Partners, Unity Mine Group, Character Group, and a UK asset manager in a litigation, leading to a sale of €75 million of subordinated securities to a U.S. bank.

Philadelphia-native Duane Morris is an AmLaw 100 law firm, taking in revenues of $491 million in 2017-18, with profits per equity partner exceeding $1 million. It has 671 lawyers around the world, including 126 equity partners.