Chris Wattie / Reuters Justin Trudeau speaks during Question Period in the House of Commons on Parliament Hill in Ottawa on Oct. 24, 2017.

OTTAWA — The Prime Minister's Office has hired a prominent employment law firm to handle an investigation into allegations against one of its senior staffers.

The PMO has asked Rubin Thomlinson LLP to be the independent, third-party investigator dealing with the complaint process involving Claude-Eric Gagne, deputy director of operations for Prime Minister Justin Trudeau.

Janice Rubin, who was hired by the CBC to lead the third-party investigation into allegations against former radio show host, Jian Ghomeshi, is a partner at the firm, but the PMO would not say whether she is involved.