Albert E. Smart

SAN ANTONIO — An Army reservist from San Antonio died on his second tour of duty in the Middle East from an illness not related to combat, the Defense Department said.

Lt. Col. Albert Smart, 41, died Friday in Doha, Qatar, a key logistics hub for U.S. forces deploying to Iraq and Afghanistan.

The Pentagon provided no details about Smart’s death, which occurred little more than a month after his unit redeployed to Afghanistan for a 12-month tour.

Smart was a computer networking specialist assigned to the 321st Civil Affairs Brigade, based at Fort Sam Houston. He previously served in Afghanistan from July 2003 to May 2004, Staff Sgt. Raymond Soto, a brigade spokesman, said Tuesday.

Soto said the brigade was trying to get more information about circumstances surrounding Smart’s death.

He said Smart, who worked full-time for the brigade,...