On Friday, U.S. officials announced the arrest of Christopher Ahn, a U.S. Marine veteran implicated in the raid of the North Korean embassy in Madrid this past February. During the raid, embassy staff were restrained, with some reported to have been beaten, before the 10-person group left with a variety of stolen electronics, including computers and cell phones.

Ahn was first taken into custody by U.S. Marshals on Thursday, according to an agency statement. He stands accused of being one of 10 individuals who carried out the February raid only days before President Trump’s ill-fated Hanoi summit with North Korea’s Kim Jong-un. Responsibility for the raid has been attributed to a group known as the Cheollima Civil Defense, also known as Free Joeon, an organization that calls for the overthrow of North Korea’s supreme leader. The group became known shortly after the assassination of Kim Jong-un’s half brother, Kim Jong-nam.

Jong-nam was said to be first in line to take control of the North Korean state following his father’s death, but an embarrassing incident involving traveling out of the nation using a forged passport to take his family to Tokyo Disneyland cost him his father’s favor. Many within the North Korean populace still held Kim Jong-nam in high esteem, though, making his presence a threat to Kim Jong-un’s dubious leadership. Shortly after Jong-nam’s assassination (which has been tied directly to Kim Jong-un), the Cheollima Civil Defense announced that a prominent member of this organization, Adrian Hong, had repeatedly asked Jong-nam to serve as a resistance leader against his half brother.

“He asked Kim Jong-nam multiple times to serve as the insurgent leader, only to be met with rejection,” said Kim Jung-bong, a South Korean academic who worked at Seoul’s National Intelligence Service until 2007.