Simpson Thacher & Bartlett has hired Allen & Overy’s (A&O) former competition co-head John Terzaken in the US.

Terzaken has been a partner at A&O for over five years, joining the magic circle firm from the US Department of Justice in 2012.

He served as director of criminal enforcement of the DOJ’s antitrust division between 2010 and 2012, handling many high-profile global cartel investigations including probes relating to the LIBOR banking scandal, LCD televisions and air cargo.

Prior to taking on a governmental role, Terzaken started his private practice career at Morgan Lewis & Bockius and Ropes & Gray.

Terzaken will join Simpson Thacher’s Washington DC office, becoming a partner in its litigation department.

He represents domestic and global clients in government enforcement and private litigation of matters involving cartel and antitrust violations. He has also led on market investigations and antitrust compliance issues.

At A&O, Terzaken was co-head of the firm’s global competition practice alongside Antonio Bavasso. He also led its Washington DC investigations and litigation group, which recently welcomed two new partners from Cadwalader Wickersham & Taft – Gregory Mocek and Anthony Mansfield – who joined when their former firm closed its Houston office.

A&O has been pushing ahead with expanding its US capabilities this year, hiring four lateral partners to its finance team. The three laterals were from White & Case and Proskauer Rose, while Milbank associate Todd Koretzky also made the move.

It also recruited a three-partner finance team from Paul Hastings this year.

A&O opened its Washington DC office in 2011 hiring a team from O’Melveny & Myers. One of those partners – Barbara Stettner – still leads A&O’s office in the US city. David Slade serves as senior partner, while Chris Salter is a partner in the financial service team.

Litigation head Tim House relocated to New York earlier this year to take on the role of the firm’s senior partner for the US. His appointment followed the loss of former US senior partner Kevin O’Shea to Milbank Tweed Hadley & McCloy last year along with two real estate partners.