The allegation was made by a California professor writing in a recent edition of The Nation magazine who quoted Marina Lowe, an ACLU staff attorney in Salt Lake City.
The article, posted online Dec. 17, asserted that ICE agents throughout the nation use all kinds of ruses, including posing as missionaries and insurance agents.
Immigration and Customs Enforcement (ICE) spokeswoman Virginia Kice on Monday said the allegation that agents pretend to be missionaries is "patently untrue."
Lowe told The Salt Lake Tribune that she had little to go on when a woman living along the Wasatch Front reported last spring that ICE agents may have posed as LDS missionaries.
The woman, who was suspicious of other visitors seeking her husband around the same time, said two people dressed like missionaries, but lacking black name badges commonly worn by Mormon emissaries, came to her door, Lowe said.
"It was purely her impression," Lowe said. "She was very suspicious."
The day after she confirmed for the visitors that her husband lived there, the article said, he was arrested by ICE agents.