When the judge asked if he was taking any form of medication, he answered yes. But, indicated it did not affect his ability to understand the charges against him.
Previously, he entered a not guilty plea at his federal arraignment for four other counts.
Atwater's attorneys asked the court to postpone his federal trial in November, saying jury selection would be challenging. They also argued the selection would likely take several weeks possibly conflicting with the holiday season.
The judge denied that request and Atwater will stand trial in November.
He is one of the men accused of murdering UNC's former student body president.
With the newest indictment, Atwater is closer to a federal death penalty trial. That charge was announced earlier this month.
Authorities say Atwater, who was 21 at the time of the murder, fired the final shot that killed 22-year-old Eve Carson.
The new indictment also lists eight special findings, which are the aggravating circumstances needed to obtain a federal death penalty.
Police and prosecutors believe Atwater and Lawrence Lovette kidnapped Carson from outside her home Chapel Hill home on March 5, 2008. Lovette was 17 years old at the time of the murder and will not face the death penalty.
The suspects are accused of forcing Carson to withdraw money from ATMs and then shooting her in a neighborhood near the UNC campus.