Lt. Col. David E. Cabrera, 41, a faculty member and the director of social work at the Uniformed Services University of the Health Sciences in Bethesda, did not have to go to Afghanistan, his wife said.

But, she said, Col. Cabrera, who held a PhD in social work from Catholic University, volunteered.

“He really had a servant’s heart,” August Cabrera said. “He loved serving soldiers.”

Col. Cabrera, who had been at the Bethesda facility since February 2010, was killed Oct. 29 in Kabul province, along with three other soldiers. Their vehicle was attacked by a makeshift bomb carried in a vehicle, the Pentagon said.

A native of Florida who went to high school in Houston and graduated from Texas A&M University, Col. Cabrera was a licensed clinical social worker and assistant professor of family medicine at the Uniformed Services University.

He had joined the Army’s Medical Service Corps in 1996. During 15 years on active duty, he had served overseas and in the United States, including the period from 2002 to 2005 when he was assigned to Walter Reed Army Medical Center and lived in Silver Spring. He was deployed to Iraq for five months in 2006.

At the university, he combined teaching military medical students with seeing patients and conducting research in such areas as resilience and post-traumatic stress disorder.

He was known at the university for an infectious smile and easygoing nature.

Besides his wife and two sons who live in Maryland, survivors include his first wife, Angela; a son and a daughter who live in Texas; and his father, stepmother, and 13 brothers and sisters.

On Sept. 30, he left for Afghanistan.

He believed that mental-health services should be provided to troops in the field as well as after they return, his wife said. “He knew there was such a need,” she added, “or he wouldn’t have gone.”