Duvall McClellan "Mac" Williams, Jr. (born 6 February 1943)[1] is a retired rear admiral of the United States Navy who was a commander of the United States Naval Investigative Service.

[2] His tenure included the time of the Tailhook scandal; he and Rear Admiral John E. Gordon were tasked with conducting the investigation.

[3] After their report was subject to harsh criticism by the Pentagon in 1992, Williams and Gordon resigned.

[6] After law school, he was commissioned as a reserve officer in the Navy Judge Advocate General's Corps.

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