JACKSON, Miss. — A relative of Emmett Till is suing to try to make a Mississippi sheriff serve a 1955 arrest warrant on a white woman in the kidnapping that led to the Black teenager’s brutal lynching. The torture and killing of Till in the Mississippi Delta became a catalyst for the civil rights movement after his mother insisted on an open-casket funeral in Chicago and Jet magazine published photos of his mutilated body. Last June, a team doing research at the courthouse in Leflore County, Mississippi, found an unserved 1955 arrest warrant for Carolyn Bryant, listed on that document...