(CNN) -- A second man charged with murder in the 2011 disappearance of Tennessee nursing student Holly Bobo told a judge he was innocent Wednesday.
Jason Wayne Autry, who is already in prison for an unrelated assault conviction, was indicted on especially aggravated kidnapping and first-degree murder charges by a special grand jury on Tuesday, Tennessee Bureau of Investigation Director Mark Gwyn said.
Autry, 39, was a longtime friend of Zachary Adams, 29, who was indicted last month on the same kidnapping and murder charges.
"Your honor, I want to say one thing -- I'm innocent of these charges. Right hand before God, I'm innocent, sir," Autry said in court.
Adams also appeared Wednesday in court, where a not guilty plea was entered for a coercion of a witness charge.
Bobo was 20 when she was last seen on April 13, 2011. Her brother told authorities he saw a man in camouflage leading her away from their home in the small town of Darden, Tennessee.
Information from "several witnesses" led to charges against Autry, Gwyn said.
Investigators "believe there are more people with information and possible involvement," Gwyn said. He told reporters to "expect more announcements in the coming days and weeks."
"These individuals know who they are, and I'm sure they are watching, and they can expect us to be on their doorstep pretty soon," Gwyn said.
The Bobo case rocked the largely rural swath of central Tennessee. Many knew the young woman and many rallied behind the effort to find her.
Hundreds of volunteers turned out to help find her in Decatur, Henderson, Henry, Carroll and Benton counties. Many more attended memorial services or offered other support. More than $450,000 has been offered in reward money.
Bobo's body has not been found three years after her disappearance.
CNN's Alan Duke contributed to this report.