"As you know, there is a federal investigation related to Ms.Carson's killing which was opened on March 14, 2008, " U.S. Attorney Anna Mills Waggoner said in a written statement to the Orange County District Attorney's Office.
"The unsealing of these search warrant affidavits would be detrimental to the federal investigation, which is ongoing," Waggoner explained.
The letter does not specify what charges--if any-- federal prosecutors could pursue against Laurence Lovette, Junior,17, and Demario Atwater,22. A federal spokesperson said no charges have been filed to date.
Investigators believe Carson was taken near her Chapel Hill home on the morning of March 5. Federal law allows for criminal charges punishable by the death penalty, if a car jacking results in a fatality.
An autopsy report that was previously sealed under a judge's order revealed the student body president was shot five times. Lovette and are facing several charges, including first degree murder, robbery and kidnapping.
A Rule 24 hearing to determine if Atwater could face the death penalty if convicted is set for August 11.