ROCHESTER — Family and friends of a Winona State University graduate who died in Vietnam under unexplained circumstances have launched a letter-writing campaign to get the U.S. government to seek answers.

Kari Bowerman, 27, of Lake Geneva, Wis., and her friend, Cathy Huynh, 26, of Hamilton, Ontario, became sick and died shortly after they arrived in Vietnam in late July for a vacation. Their families say they’ve been unable to obtain an explanation of why they died from Vietnamese authorities or U.S. consular officials in Vietnam.