Gabriel Marchal was a person of interest in the joint NCIS/H50 investigation into a supposed plot to unleash smallpox on the world.
According to Nell Jones, Marchal was also a member of ELE- "Enhancing Law Enforcement", a homegrown militia group that appeared in the NCIS: Los Angeles Season 1 episode, "Ambush" but thanks to the efforts of Special Agent G. Callen, Special Agent Sam Hanna, Detective Danny Williams and Lieutenant Chin Ho Kelly, Marchal was eventually arrested, interrogated and presumably jailed.