Murder of Peter P. Keen
In late December of 1862, however, two and a half years after the crime, an investigation was undertaken after several letters passed through the Holden post office addressed to Andrew J. Wallace, giving his address as Frankford, Illinois. (This might have been a misspelling of Frankfort.) Three citizens of Johnson County, including Keen's widow, promptly offered their testimony about Wallace's involvement in the killing of Peter Keen.
Harriett Keen said she knew Wallace was one of those who had participated in the murder of her husband and that Wallace was known in the area at the time as a notorious bushwhacker.
Elijah Buchanan echoed Mrs. Keen's testimony, saying that, at the time of the murder, he was close enough to the scene of the crime to hear the gunfire, that he saw the gang of bushwhackers immediately afterward, and that Wallace was one of them.
Holden postmaster William Rose (who no doubt was the one who called attention to the letters addressed to Wallace) said that Wallace and his comrades had taken him prisoner on the same day Keen was killed and had threatened to kill him, too. Rose said the bushwhackers spared him only because his father-in-law pled with them to do so. Rose added that the bushwhackers said in his presence that they "would kill every damned Union man in the county" or any man who went among the Federal soldiers. Rose said that Wallace had been a schoolteacher before the war and that he thought he was also teaching school in Illinois.
Apparently Wallace was never brought back to central Missouri to answer the charge of killing Peter Keen, or if he was, he was not detained long. He spent most of his adult life in the Decatur, Illinois, area and died there in 1908.