Brian Wright was a Sergeant in the United States Marine Corps who served three times in Iraq and was left injured.
As such, he became homeless and started living on the streets.
At some point, Luis Romero let him stay in the hotel. Wright came across a man strangling or killing an underage Chinese girl and attempted to save her life by performing CPR, only to be thrown over the edge just as a conference involving many federal agencies including NCIS was held.
Due to Wright being a Marine, NCIS got full access and control of the case and were successful in arresting Wright's murderer.