ALBUQUERQUE -- As a boy, the Rev. William Sanchez sensed that he was different. His Catholic family spun tops on Christmas, shunned pork, and whispered of a past in medieval Spain. If anyone knew the secret, they weren't telling, and Sanchez stopped asking.
Then three years ago, after watching a program on genealogy, Sanchez sent for a DNA kit that could help track a person's background through genetic footprinting. He soon got a call from Bennett Greenspan, owner of the Houston-based testing company.
"He said, 'Did you know you were Jewish?' " recalled Sanchez, 53. "He told me I was a Cohanim, a member of the priestly class descended from Aaron, the brother of Moses."
With the realization that Sanchez was almost certainly one of New Mexico's hidden or crypto-Jews, his family traditions made sense to him.
He tested the DNA of his relatives, along with some of the parishioners at Albuquerque's St. Edwin's Church, where he works. As word got out, others in the community began contacting him. So Sanchez expanded the effort to include Hispanics throughout the state.
Of the 78 people tested, 30 are positive for the marker of the Cohanim, whose genetic line remains strong because they rarely married non-Jews throughout a history spanning up to 4,000 years.
Michael Hammer, a research professor at the University of Arizona who is a specialist on Jewish genetics, said less than 1 percent of non-Jews possessed this marker. That fact, along with the traditions in many of these families, makes it likely they are Jewish, he said.
"It makes their stories more consistent and believable," Hammer said.
It also explained practices that had baffled many folks here for years: the special knives used to butcher sheep in line with Jewish kosher tradition, the refusal to work on Saturdays to honor the Sabbath, the menorahs that had been hidden away.
In some families, isolated rituals are all that remain of a once-vibrant religious tradition diluted by time and fears of persecution.
Norbert Sanchez, 66, recalled the "service of lights" on Friday nights in his hometown of Jareles, in which some families dined by candlelight.
"We always thought there was a Jewish background in our family, but we didn't know for sure," he said. "When I found out, it was like coming home for me."
In 1492, Jews in Spain were given the choice of conversion to Catholicism or expulsion. Many fled, but others faked conversions while practicing their faith in secret. These crypto-Jews were hounded throughout the Spanish Inquisition.
"In the 1530s and 1540s, you began to see converted Jews coming to Mexico City, where some converted back to Judaism," said Moshe Lazar, a professor of comparative literature at the University of Southern California and a specialist on Sephardic Jews, or those from Spain and Portugal. "The women preserved their tradition. They taught their daughters the religion. People began rediscovering their Jewishness but remained Catholics."
But in 1571, the Inquisition came to Mexico. Authorities were given lists to help identify crypto-Jews, Lazar said. People who did not eat pork, knelt imperfectly in church, rubbed water quickly off newly baptized babies, or did not work Saturdays were suspect. If arrested, they were sometimes burned at the stake.
Many fled to what is now northern New Mexico and remained secretive even after the United States gained control of the area in 1848.
"No one would come out and say, 'I am a Jew.' That didn't happen until the 1970s," said Stanley Hordes, a professor at the Latin American and Iberian Institute of the University of New Mexico who is writing a book on crypto-Jews. "The first few generations kept the secret because of danger of physical harm, and later they kept it because that was just what they did. The $64,000 question is: Why the secrecy today? Why are people keeping this information from their kids and grandkids?"
Some have not.
"I found out when I was 13," said Keith Chaves, 47, an engineer in Albuquerque. "My great-grandmother told me that we were 'Sepharditos.' "
The family matriarch was a repository of knowledge, and the keeper of secrets.
"She kept a kosher knife rolled up in a piece of leather that she would only use for killing," Chaves said. "And she would kill the animal by cutting its throat in one motion. She abhorred the ways others killed animals."
Born a Catholic, Chaves attends an Orthodox synagogue in Albuquerque. He has made four documentaries on crypto-Jews and is working on a movie about his family history.
"When I found out about my roots, I went to the library and my world opened up. I started peeling what turned out to be a 500-year-old onion," he said. "I have reclaimed my life. I live a Jewish life now. I think my great-grandmother told me because she expected me to do something fruitful with the information."
DNA test participants scrape cells from the inside of their cheeks and mail samples to Greenspan, who has them analyzed by researchers at the University of Arizona. The cost ranges from $100 to $350, depending on the detail requested. Women, who do not possess the Y chromosome, must have a male relative take the test to participate.
Since uncovering his past, the Rev. Sanchez -- who wears a Star of David around his neck -- has traveled throughout the state giving talks on the history and genealogy of New Mexico. He also runs the Nuevo Mexico DNA Project and website that tells how people can participate.
Sanchez describes his Jewish history as "a beautiful thing" complementing, not conflicting with, his priestly life. "I have always known I was Jewish; I can't explain it, but it was woven into who I was," he said.
After Mass one recent morning, a group of parishioners filed out of St. Edwin's. None said they had a problem with their priest's dual religious traditions.
"He has taken us back to our roots," Robert Montoya said.
Theresa Villagas smiled. "We are all children of God," she said. "I think this just adds richness to our lives."