An al-Qaida-linked group led by Abu Musab al-Zarqawi claimed Tuesday to have killed the second of two American hostages — back-to-back slayings that have notched up the Jordanian militant’s ruthless campaign of terror. The claim, posted on an an Islamic Web site, could not immediately be verified. Al-Zarqawi’s group, Tawhid and Jihad, kidnapped two Americans — Jack Hensley and Eugene Armstrong — and Briton Kenneth Bigley on Thursday from a home that the three civil engineers shared in an upscale Baghdad neighborhood. Al-Zarqawi beheaded Armstrong, and the militants on Monday posted a gruesome video of the 52-year-old man’s death. Full Story