FOR SENIOR WRITER RON ARIAS, Covering the mysterious death of Tammy Jo Zywieki (page 30) had a profound impact. "I have tremendous empathy for people who have lost a family member," says Arias, 51, whose son Jonathan died at age 6 in a car accident 15 years ago. "Jonathan's death was the toughest thing that ever happened to me."

Since last September, when Tammy's body was found along the highway near Joplin, Mo., Arias has spent a good deal of his time trying to unravel the mystery with her parents—Hank, 53, and JoAnn, 51—and her brothers—Todd, 27, Dean, 26, and Daren, 20. Tammy, a 21-year-old senior at Grinnell College in Iowa, was sexually assaulted and murdered en route to school. The case received national attention when it initially aired last August on America's Most Wanted, but it remains unsolved.

When the first stories appeared, managing editor Landon Y. Jones assigned Arias to explore the aftermath of the tragedy over the course of a year. "I was asked to report the hell out of it," says Arias, "and write with a lot of heart. From the beginning, that meant sitting around watching for little things and being super patient." Fortunately he had photographer Michael Carroll, 46, for company. "The biggest challenge for me was to bring out the emotions that were right below the surface," says Carroll. "The Zywickis are like my relatives. They don't show their emotions. They're not outwardly affectionate, although they love one another deeply."

Arias and Carroll clicked as a team. "Whenever I would have slow moments in an interview," says Arias, "Mike would just jump right in and ask questions." Their detective mission look them from New Jersey to South Carolina to points all over the Midwest interviewing Tammy's friends and the police. Says Alias about working in the field: "It's like walking onto an Indiana Jones set. Only, it's for real, and you're the guy that's got to run and keep up."

Arias, who was born in Los Angeles, the second of three children of Armando, an Army major, and Emma, a homemaker, first became interested in journalism when he had his tonsils removed at age 9. At the hospital, his mom gave him a writing pad and told him to take notes on everything he saw. "From then on," he says, "I wanted to be a writer."

In 1961, at age 20, he got his first real assignment: chasing tanks in Buenos Aires while covering coups for the Associated Press. After earning a B.A. in Spanish and an M.A. in journalism at UCLA, he taught English and journalism in San Bernardino, Calif., for 13 years. But in 1985 he gave up teaching to join PEOPLE'S staff, as he says, "to get back into writing and not just talk about it."

Now Arias has several hundred stories to his credit, some of them written in such far-flung places as Baghdad and Somalia. But the one he hopes will have the most impact is the story that appears in this issue. "I hope this piece will help solve the case," he says confidently. "Somebody is going to come forth."