Oakland Police Sgt. Lee French and his wife, Richmond Police Chief Bisa French, are on leave and under investigation, after a domestic violence restraining order was filed against them by a relative who claims they pinned her down and threatened her boyfriend and his family. The Oakland Police Department Thursday confirmed that Lee French was put on leave and said an internal investigation is underway into “criminal allegations.” In court documents, 18-year-old relative accused the Frenches of attacking her and…