Gerry Adams has reportedly been held overnight at a police station in Northern Ireland.
The Sinn Fein leader will face more questioning this morning over the murder of mother-of-10 Jean McConville in 1972, Sky News reports.
Mr Adams has issued a statement saying he is "innocent of any part in the abduction, killing or burial of Mrs McConville".
Adams attacks reasons for his detention and denies McConville murder
It is claimed IRA volunteers described what happened the night Jean McConville was murdered to Boston College's "Belfast Project".