This is news. The Associated Press reports that one unit of the FBI had information that McVeigh sought help from a group of white supremacist bank robbers days before the Oklahoma City Bombing, and failed to share the information with the FBI unit investigating the bombing:

The FBI believed Timothy McVeigh tried to recruit additional help in the days before the deadly 1995 Oklahoma City bombing and gathered evidence that white supremacist bank robbers may have become involved, according to government documents never introduced at McVeigh's trial.

The retired FBI chief of the Oklahoma City investigation, Dan Defenbaugh, said he was unaware of some evidence obtained by The Associated Press and that the investigation should be reopened to determine whether the robbery gang was linked to McVeigh.

The evidence never shared with Defenbaugh's investigators or defense lawyers includes documents showing the Aryan Republican Army bank robbers possessed explosive blasting caps similar to those McVeigh stole and a driver's license with the name of a central player who was robbed in the Oklahoma City plot.

Does this mean others were involved?

McVeigh's ex-lawyer said the evidence obtained by the AP is the strongest to date to show what he has argued for years -- that the bombing conspiracy may have involved more people than McVeigh and Nichols.

"I think these pieces close the circle, and they clearly show the bombing conspiracy consisted probably of 10 conspirators," attorney Stephen Jones said. "They (government officials) simply turned their backs on a group of people for which there is credible evidence suggesting they were involved in the murder of 160 people."

Some of the original documents cited in the article are available here.

You can read more from older news articles here and here.