Jaehoon Ahn, a Washington Post researcher for more than 25 years who went on to become founding director of Radio Free Asia’s Korean-language service, died June 1 at a hospital in Virginia Beach of complications from a bleeding ulcer. He was 70.

Mr. Ahn was a native of North Korea whose family fled the country after the Communist Party took control at the end of World War II. Before moving to the Washington area in the late 1960s, he was a reporter for one of South Korea’s largest newspapers.

He was an assistant librarian in The Post’s research department from 1969 to 1996. In retirement, he worked briefly as a consultant to a Seoul daily newspaper, where he was charged with helping restructure the newsroom and create a style section.

He left that job in 1997 to help congressionally funded Radio Free Asia start a new Korean-language service.

He began from scratch and within six weeks had helped hire five reporters and get a half-hour broadcast on the air. His team soon built a longer program and a reputation for reporting from North Korea, one of the world’s most closed countries.

Mr. Ahn retired from Radio Free Asia in 2007. He moved to Sandbridge Beach, near Virginia Beach, but continued working on North Korean issues as a member of the board of directors of the Washington-based Committee for Human Rights in North Korea.

Jaehoon Ahn was born May 13, 1941, in Pyongyang. He was 5 when his family left in the middle of the night to become refugees in South Korea.

Mr. Ahn received a bachelor’s degree in 1960 from Seoul National University. He covered the 1967 Arab-Israeli War as a Middle East correspondent for the South Korean newspaper Joong-ang Ilbo.

He was a member of the Korean United Methodist Church of Greater Washington.

Survivors include his wife of 42 years, Soonhoon Lee Ahn of Sandbridge Beach; two daughters, Soomie Lee Ahn of Manila and Yoomie Lee Ahn of Richmond; four sisters; a brother; and three grandchildren.