Billy Flynn testifies in the Pamela Smart murder trial. CONCORD, N.H. —When 16-year-old Billy Flynn gunned down the husband of his high school instructor and lover, Pamela Smart, in 1990, the trial became an instant tabloid sensation. Its lurid details aired gavel-to-gavel on television years before the O.J. Simpson spectacle and spawned movies and books. Twenty-five years after Gregg Smart's killing, Pamela Smart remains in prison serving life without the possibility of parole and Flynn makes his first bid for parole Thursday, his 41st birthday. Flynn pleaded guilty to second-degree murder and testified in Smart's 1991 trial that she...