He was the son of Col. David Breakenridge McNeil (born 1787, in Charlotte, Vermont, District Attorney of Essex County from 1828 to 1833, and Collector of the Port of Plattsburgh during the administration of President Andrew Jackson).
Then he worked in the office of the Secretary of State of New York under David R. Floyd-Jones and Horatio Ballard (1860–1863).
As to his successor in that respect, we leave the matter to general rumor.
"[1] In 1863, he ran on the Democratic ticket for Inspector of State Prisons but was defeated by James K. Bates.
In 1864, he ran again for Inspector of State Prisons but was defeated by David P. Forrest.