Editor's note: Last of four articles.

A, B, C, D.

These four letters represented the first DNA classifications of Native Americans into similar lineages, or haplogroups.

Things were simpler then — and so were the conclusions.

Because A, B, C and D appear to be Asian in origin, some said this proved the Book of Mormon false. But even then, a simple understanding of DNA showed that it would have been possible, or even probable, that we wouldn't find traceable DNA evidence from a small group of Israelites coming to a largely populated continent.

Enter X.

A few years later, the story became more complicated. A fifth haplogroup was found in Native Americans. Ironically, the letter chosen to identify the new haplogroup was the mysterious letter X. "Studies confirmed the presence of X in the Americas," said Ugo Perego, senior researcher at Sorenson Molecular Genealogy Foundation, "particularly in the Great Lake regions of northern North America — but also in other areas to a lesser extent such as Texas, New Mexico and Arizona."

Read the full story on MormonTimes.com.