The family of kidnapped British journalist Alan Johnston pleaded Monday for his captors to "end this ordeal" following unconfirmed reports he has been killed. The BBC said it could not confirm the claim by a previously unknown Palestinian group that it had killed Johnston, the BBC's Gaza correspondent. Johnston, 44, was abducted by gunmen after leaving his office in the Gaza Strip on March 12. On Sunday, a previously unknown group calling themselves The Brigades of Tawheed and Jihad said it had killed Johnston to support demands for the release of Palestinian prisoners held by Israel. Palestinian officials said they could not confirm the claim and Britain's Foreign Office said it was "urgently" investigating the reports.