South Korean police are looking into a possible connection between the man who attacked the U.S. ambassador to Seoul and his several visits to North Korea, a senior official said Friday. Police are also seeking a detention warrant for Kim Ki-jong on charges that include attempted murder. The 55-year-old attacked U.S. Ambassador Mark Lippert on Thursday, in what appeared to be a protest against the annual U.S. and South Korea joint military exercise. Kim visited North Korea seven times between 1999 and 2007, said Yoon Myeong-seong, chief of police in Seoul’s central Jongno district. Kim will also face assault charges as well as obstructing business operations. Police have discovered Kim is a member of the pro-unification group that hosted the forum the ambassador was attending.