Kim Jong-un allegedly arranged more than one assassination.
Aside from his half-brother, the North Korean leader also ordered the killing of two men who helped with the defection of Thae Yong-ho, the North Korean diplomat in London who defected to the South last year.
According to Radio Free Asia on Wednesday, UK's Minister of State of the Foreign and Commonwealth Office - Joyce Anelay - said authorities will investigate whether there's a credible threat to the safety of a British national or resident.
Earlier this month, U.K. newspapers The Sun and The Sunday Express reported that North Korea's Radio Pyongyang broadcast a coded message ordering the murder of a British and an American national believed to have helped Thae defect.
This would be the first assassination order to target foreign nationals.
Measures have been taken to protect the regime's targets.