New claims about the Oklahoma City bombing say the FBI left a key figure uninvestigated, which is bad for the bureau's credibility and reopens doubts about the official one-bomber story.

• The evidence does not fit the official account that Timothy McVeigh acted essentially alone.
• A German national, Strassmeir, made repeated trips to Oklahoma while a bombing was being planned.
• The FBI never interviewed him, even though McVeigh called him minutes after calling the Ryder truck company.
• The simplest explanation offered for that gap: he was working for the government.
• He is still alive and, as far as is known, has never been questioned in person.

Outlook: Expect more pressure on the FBI to explain the gaps, though the bureau has stayed silent on the case for decades.