BRENTWOOD, N.H. — Attorneys for a Stratham lawyer accused of killing his ex-wife say they have filed motions in an attempt to nullify the grand jury process.

Seth Bader, 37, was indicted on charges of first-degree murder, simple assault and criminal threatening last week.

Police said he and his former fiancee, Mary Jean Martin, 33, and a Massachusetts man, Sandro Stuto, 22, conspired to kill Vicki Bader.

Seth and Vicki Bader were involved in a bitter custody battle over their 3-year-old son Sam when she disappeared last August, shortly before she was expected to regain custody of the child.

Seth Bader was arrested in April after his 15-year-old adopted son, Joseph Bader, told police he helped his father bury Vicki Bader’s body in the woods in rural Maine, police said.