It was a burglary that was a mystery to the investigators: shortly before a meeting of US President Donald Trump with North Korea's dictator Kim Jong Un, a group had stormed the North Korean embassy in Madrid. Now, a former US Marine in the US has been arrested in connection with the burglary.

The man was brought to a Los Angeles court on Friday, the Washington Post reported. The suspect should belong to the political group "Free Joseon", which calls for a fall of the North Korean ruler Kim.

The collapse of the Embassy of the isolated communist country in the Spanish capital had occurred a few days before Trump met Kim on February 27 in Hanoi. This computer and other items were stolen. Details remained unclear, reports of Spanish newspapers at that time suggested a connection of several parties to the US foreign intelligence service CIA.

"The last US citizen detained by the Kim regime did not survive"

In March, "Free Joseon," also known as "Cheollima Civil Defense," declared itself responsible for the break-in. She has since shared "tremendous potential value" information with the Federal Bureau of Investigation (FBI).

A statement on their website said the group was "dismayed" that the US Department of Justice issued arrest warrants for US citizens based on criminal charges from North Korea. "The last US citizen to be arrested by the Kim regime returned home in torture and did not survive," the statement said in reference to student Otto Warmbier.

Warmbier was arrested at the beginning of 2016 after a group tour in North Korea on departure and sentenced to 15 years in a labor camp for "hostilities against the state". In 2017, he was released and returned to the US. He died a couple of days later. Warmbier had been in a coma for 15 months.