Barbara Mertz, an Egyptologist who wrote best-selling mysteries and supernatural thrillers, many of them set in the Middle East, under the pen names Elizabeth Peters and Barbara Michaels, died on Aug. 8 at her home in Frederick, Md. She was 85.

The cause was complications of a pulmonary embolism, her daughter, Elizabeth Mertz, said.

Ms. Mertz wrote nearly 70 books, beginning with two, under her own name, about Egypt, “Red Land, Black Land: Daily Life in Ancient Egypt” and “Temples, Tombs and Hieroglyphs: A Popular History of Ancient Egypt.”

“She writes with an informal grace and contagious enthusiasm rarely found in books by qualified scholars,” Orville Prescott wrote in The New York Times in his review of “Temples, Tombs and Hieroglyphs.”

Ms. Mertz completed three novels before writing “The Master of Blacktower” (1966). At her agent’s request, she used the name Barbara Michaels. She was so relieved to finally sell a novel, she told The Washington Post in 1989, that “I would’ve accepted the pen name Jack the Ripper.”