Updated at 3:55 p.m. ET on 7/15
(CNN) – President Barack Obama, who on Sunday called the killing of Trayvon Martin a tragedy, will not involve himself personally in deciding whether to bring federal civil rights charges against Martin's killer George Zimmerman.
"That is not something the president involves himself in," White House Press Secretary Jay Carney told reporters Monday when asked about potential federal charges against Zimmerman, who was found not guilty of murdering Martin by a jury on Saturday.
"He has no opinion to express about the disposition about how the Justice Department will look at this," Carney continued.
Civil rights groups, including the NAACP, have called on Attorney General Eric Holder to pursue federal charges against Zimmerman. Petitions sponsored by the NAACP had already garnered almost 800,000 signatures as of Monday afternoon, while separate petitions on the White House's own website had gained nearly 15,000 supporters.
Speaking at the 100th anniversary celebration of the Delta Sigma Theta sorority in Washington Monday, Holder said the Justice Department is investigating possible federal charges in Martin's killing, adding in prepared comments it will "continue to act in a manner that is consistent with the facts and the law." Holder has previously cited a tough standard for bringing federal charges against Zimmerman.
"Independent of the legal determination that will be made, I believe that this tragedy provides yet another opportunity for our nation to speak honestly about the complicated and emotionally-charged issues that this case has raised," Holder said. "We must not – as we have too often in the past – let this opportunity pass."
Carney, responding to a question from CNN chief White House correspondent Jessica Yellin about increased pressure on Obama's administration to act quickly on bringing federal charges, asserted that established procedures would continue to be followed, despite the swelling outrage.
"Cases are brought on their merits, and the merits are evaluated by professionals at the Department of Justice, and the president expects as in every case that the process will be handled at the Department of Justice and not here," Carney said.
On Sunday, less than 24 hours after the verdict came down, Obama released a statement urging Americans to respect calls for calm in the aftermath of the jury's decision.
The president, in the written statement, acknowledged an emotionally charged climate but concluded that "we are a nation of laws, and a jury has spoken."
Obama's first comments on the Zimmerman trial came in March 2012, when the president said the fatal shooting of an unarmed African-American teen required national "soul searching."
The president also personalized the shooting in those remarks. He told reporters he thought about his own children when he thought about Martin.
"I think every parent in America should be able to understand why it is absolutely imperative that we investigate every aspect of this and that everybody pulls together - federal, state and local - to figure out exactly how this tragedy happened," Obama said at that time.
CNN's Kevin Liptak contributed to this report.