Prosecutors said Wednesday that they will seek the death penalty for three men charged with murder in the 2011 disappearance and killing of a Tennessee nursing student if they are convicted at trial.

Special prosecutor Jennifer Nichols acknowledged in Decatur County court that notices to seek death had been filed.

"The murder was especially heinous, atrocious or cruel in that it involved torture or serious physical abuse beyond that necessary to produce death," the filings say.

An indictment handed down in May charges Jason Autry, Zachary Adams and his brother John Dylan Adams with premeditated murder as well as murder in the perpetration of aggravated kidnapping and aggravated rape of Holly Bobo.

The indictment replaced previous murder and kidnapping charges for Autry and Zachary Adams, and rape charges for John Dylan Adams. Charges against the men are now combined into one case under a single indictment. All three men pleaded not guilty Wednesday. Autry was heard declaring his innocence on his way back to jail, MyFoxMemphis.com reported.

Bobo was 20 when she was reported missing from her home in Parsons in rural West Tennessee in April 2011. Her disappearance and the subsequent lengthy search attracted national attention. Authorities say her skull was found in the woods in Decatur County in September.

Matt Maddox, attorney for John Dylan Adams, said he was surprised at the timing of the filings to seek the death penalty, but he added that he preferred receiving the notices "sooner rather than later."

Nichols said the filings were made at the earliest opportunity after the new indictment was issued.

Judge C. Creed McGinley said the decision affects the pace of the case as it moves toward a trial.

"I'm not going to be able to move at breakneck speed as I had hoped," McGinley said.

Don Franks, a local pastor who acts as a spokesman for the Bobo family, said Wednesday "was a giant step on the road to justice for Holly."

Defense attorneys have complained that they have not received evidence against their clients from prosecutors. McGinley stated in court that prosecutors will give the evidence to the defense within 30 days.

The Associated Press contributed to this report