Rohan Weerasinghe, a former Shearman & Sterling senior partner who became global general counsel of Citigroup, has rejoined the New York-based law firm as of counsel ahead of its proposed merger with Allen & Overy, the firm said Tuesday.

Weerasinghe left Shearman in 2012 as a senior partner to go to Citigroup after a 35-year career at the firm. Weerasinghe's arrival back at Shearman comes as the firm is preparing for a vote in October on the proposed merger with Allen & Overy.