The diplomat visited both prisoners on December 3, 2011 (after their transfer to Ndolo prison).
The diplomat who has been named to head the American office, James H. Hall, is visiting.
When one Asian diplomat visited the camp, he was mobbed and blows were struck.
He smiled, wondering if the storied diplomat had ever actually visited the land that had once been called the last frontier.
The diplomat had just visited an open-air fruit and vegetable market before the bomb exploded, witnesses said.
American diplomats have visited him regularly, though they have not spoken publicly about the case.
Business executives and Western diplomats who have visited the area estimate that the death toll could reach 1,000.
Legal experts and diplomats regularly visit the court or otherwise analyze its experiences and procedures now that other international tribunals are getting under way.
In response to this, a government spokesman said that "Everyone knew that foreign diplomats were visiting the area today".
Senior American diplomats have applauded the new peace initiative and repeatedly visited the region since last year's war scare.