From PEOPLE Magazine Click to enlarge
Like most Montanans, Sherry Arnold was made of stern stuff. A few months back during a jog, the cattle rancher's daughter was knocked off her feet by a swerving pickup truck but shook it off and finished her route. More telling, in 2005, during grueling chemo to shrink a sarcoma in her leg, she promised, "I'm going to beat this." Recently her husband bought her a pendant inscribed with the words "I'm a Survivor." "She saw it and said, 'I want that,'" recalls Gary Arnold, who tucked it away to give to her later.

Now he'll never get the chance. Before sunup Jan. 7, Sherry, 43, a beloved high school math teacher from Sidney, Mont., brushed her teeth, laced up her sneakers and bounded off on the route she'd traveled countless times before, a 3.5-mile loop that traversed an isolated stretch of prairie-bordered truck road. When she never came home, more than 1,000 locals in a town of 5,000-many of them Sherry's pupils-fanned out across the prairie to search for her. On Jan. 12 and 13, authorities arrested two unemployed Colorado laborers for kidnapping, though no body has been found and no motive announced. In the sleepy Montana-North Dakota border town better known for bar fights than serious violence, stunned citizens struggled to come to grips with the news. "It's a shock," says Sidney police chief Frank DiFonzo. "It's not something we ever expected to happen to us."

The great-granddaughter of the city's first police chief, the 18-year-veteran educator "was the kind of teacher you knew cared about you," says junior Chelsea Strasheim, 17. Though her own five children-including Sidney High students Holly, 15, and Jason, 17, her kids from her first marriage and three stepkids from her husband's-"came first," says friend and fellow teacher Staci Rice, Sherry regularly stayed after hours to tutor or work on podcasts so students could sharpen their skills at home. After she went missing, folks who'd never locked their doors put in new deadbolts. "Gun sales are triple what they usually are," says Blaine "Chip" Gifford, co-owner of Sidney's Johnson Hardware. Recently, due to a regional oil boom, an influx of out-of-towners looking for work spurred a spike in crime, and "things changed," admits Gifford. Since Sherry's disappearance, "people are nervous," he adds. "A lot of women don't want to go out at night."

So far, cops aren't revealing whether Sherry's kidnapping was random or targeted. All her grieving family knows is that a witness later told investigators she'd spotted someone matching Sherry's description jogging just east of Sidney's sugar-beet refinery around 6:30 a.m. It was the last anyone saw of her, save a lone running shoe police found in a field beside the truck road. Less than a week later, they arrested Lester Vann Waters Jr., 47, in Williston, N.Dak., then Michael Keith Spell, 22, in Rapid City, S.Dak., on charges of aggravated kidnapping, claiming the two men "restrained" Sherry and kept her in "a place of isolation." As the pair awaited their extradition hearing from a North Dakota jail, authorities continued to comb vacant farmsteads on the outskirts of town in search of Sherry's body. "It's a tough deal," says her sister Rhonda Whited of the agonizing wait for answers. "I don't have a clue."

And yet, wait is all her family can do. One recent evening Sherry's husband, Gary, 56, a Sidney school administrator, wept while clutching his wife's pendant. "I forgot to give it to her," he said, doubling over with grief, "and now I'll never get to." With relatives and neighbors to lean on, he and their kids are "doing the best they can," says Sherry's sister-as is the rest of their mourning town. "It's brought us all closer together."