John, I think this is another "Mr. Gregg" and not "Albert G. Gregg" from Washington Co, AR from the way this reads..Reports of cases at law and in equity argued and determined in Supreme Court of Arkansas Volume 22--By Arkansas. Supreme Court--Term 1860--Start pg 372--(Google Books)

http://tinyurl.com/3vwntt8
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Pope vs State (Excerpts)

David Pope was convicted of murder in the second degree, and sentenced to confinement in the penitentiary for the period of five years. His motion for a new trial was overruled, and he excepted, and appealed.

Gregg, the deceased, was shot by Pope with a pistol and died of the wounds inflicted, shortly afterwards. The shooting took place at Simpco's grocery, in Crawford county—Gregg standing in the porch, and Pope in the door leading from the porch into the grocery, at the time the pistol fired.
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History of Benton County (AR)--The Courts. pg 72

During “the sixties” a man named Pope killed a Mr. Gregg, near the site of Mountainburg, and after trial he was convicted, but the decision was reversed by the supreme court.

History of Benton County (AR)-Court-Houses, Trials, etc. page 631

In 1859 David Pope was tried for the murder of a Mr. Gregg, which occurred in a horse-race difficulty. Judge Gregg, a relative of the murdered man, prosecuted, with the assistance of William Walker and Judge Mansfield, and Pope was sentenced to five years for murder of the second degree.
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Gay