Nancy Hanks' lineage

[RJNorton]

I'll summarize an odd item from an old clipping on Elkins Lincoln,
One of the sons of Rev David Elkins joined the CSA and was wounded
and taken prisoner. He was, along with other prisoners, being marched through the White House grounds and was being mistreated by a Union soldier. The younger Elkins grabbed the rifle and "under the eyes of the President" clubbed the Union guard to death. Elkins was sentenced to be shot. The Reverend and his wife came to Washington and Lincoln heeded a mother's plea and pardoned young Elkins, because the Reverend had preached the funeral services of Nancy Hanks.

Can you post the source for this story? Thanks.