An Australian who wrote a book saying DNA evidence contradicts ancestral claims of Mormon belief faces disciplinary action that could get him excommunicated from The Church of Jesus Christ of Latter-day Saints.

Simon Southerton has been ordered to appear at a July 31 hearing before church leaders in Canberra, Australia, he said in a telephone interview with the Associated Press. But rather than charge him with apostasy, LDS leaders in his area have charged him with adultery.

Southerton's book, "Losing a Lost Tribe: Native Americans, DNA and the Mormon Church," was published a year ago by Salt Lake-based Signature Books, a publishing house for Western and Mormon studies. It used established DNA data to rebut Book of Mormon teachings that ancient American inhabitants were descendants of Israelite patriarch Lehi.

LDS Church members believe Lehi was an ancient seafarer who came to the New World about 600 B.C., according to church founder Joseph Smith's 1830 Book of Mormon. Smith said he translated the text from inscribed gold plates unearthed from an upstate New York hillside. His book is viewed by many members as a literal record of God's dealings with early Americans.

"We know from evidence that that's completely false," said Southerton, a plant geneticist who abandoned his church and post as an LDS bishop in 1998 in a struggle to reconcile his faith and science. "The church needs to modify its doctrine."

But Southerton, a researcher at the Commonwealth Scientific and Industrial Research Organization in Canberra, faces charges of adultery, not heresy. Southerton acknowledges he had an affair five years ago after he separated from his wife, Jane, and contends church authorities are latching onto that instead of proving more difficult charges of apostasy.

"(The letter) completely ignores what is obviously the major issue," says Southerton, who was baptized into the church at age 10 in 1970. "They've been snooping around. Clearly I should be excommunicated for the most serious offense and, in my view, apostasy is much more serious."

Southerton says church authorities never mentioned adultery when they paid him a recent visit, instead bringing up his book, his renunciation of LDS faith and his years of postings on the Web site, www.exmormons.org.

"I would have to be regarded as a threat to the church," he said.

Church officials in Salt Lake City said they were unaware of any disciplinary action being taken against Southerton. "We wouldn't, because those decisions are local," spokeswoman Kim Farah said.