The parents of Joel Shrum, 29, also rejected the idea, circulating in Yemen, that he was there as a Christian missionary. Rather, Yemen was the latest chapter in Shrum's life of seeking to help others out of poverty and build bridges between cultures.
Jim and Lynda Shrum said their son's quest began about a decade ago when he took a college trip to India to help improve conditions at orphanages.
"He had a knack with people," Jim Shrum said. "Knocking down barriers, accepting other cultures, taking the good and the bad."
The Shrums also said they feared for the safety of Joel's widow, two young sons - ages 4 and 1 - and his Yemeni friends. They said they didn't want to talk about his widow's plans out of concerns for her safety.
Shrum was killed Sunday by two gunmen on a motorcycle while driving in the city of Taiz. A text message circulated by mobile phone in Yemen afterward said "holy warriors" had killed "a senior missionary," but it was impossible to confirm the claim of responsibility.
Al-Qaida and other militant groups are active in Yemen, which has suffered a breakdown of central state authority during the country's yearlong uprising.
Taiz security director Ali al-Saidi said Monday that the investigation is still ongoing. In Washington, State Department spokeswoman Victoria Nuland told reporters that the United States is urging Yemeni authorities to bring those responsible to justice.
"We condemn this terrorist act in the strongest terms, and we express our deepest condolences to his family and his friends," Nuland said.
Shrum's parents live in Harrisburg, Pa., where they moved after raising Joel in Mount Joy, Pa., about 20 miles away.
Joel Shrum moved to Yemen three years ago with his wife, Janelle, and older son. He began working for the Swedish-run International Training Development Centre in Taiz in 2010, and eventually was promoted to deputy director, his parents said. Among the skills taught there are English as a second language, cooking and sewing, as well as how to be an electrician and how to use computers, they said.
His second son was born in Taiz. Joel Shrum also was working toward a degree in international business through an online school and believed that teaching business skills was an effective way to help people, they said. Many of the school's teachers are Yemeni, and Shrum had been able to hire some of his friends to work there, his parents said.
A protestant, Shrum was surrounded by Yemeni friends and deeply respected their Muslim faith. On a trip there to visit him in 2010, his parents met friends of Joel and Janelle and were struck by their warmth and hospitality, they said.
"We could see that their friends loved them," Lynda Shrum said.
The trip there eased their fears about their son living in Yemen. The Shrums said their son never felt targeted, although he feared the violence that broke out in Taiz in December.
The school also denied that Shrum was proselytizing, saying that he "highly respected" Islam. It said Muslims and Christians work together on "human development, skill transfer and community development" projects there and that religious and political debates are not permitted.
It also asked the Yemeni people to "reject the hatred and violence in their country."