The plea came at his initial court appearance Thursday, where a judge ordered him held without bond pending a detention hearing that has not yet been scheduled.

His attorney, Rajan Joshi, asked for bond, arguing the allegations in the 46-page affidavit failed to meet the high standard required to deny pretrial release, while the state asked that he remain in custody. The arrest warrant and affidavit remain sealed.

Joshi told the Tampa Bay Times the prosecution's case faces many challenges he plans to explore, saying the investigation focused almost exclusively on Smith from the beginning and ignored other potential leads.

"They did not go out and investigate other possibilities that could have happened to her," he said, arguing police "immediately target the usual suspect, which is the ex."

He added that Smith was cooperative when first questioned 15 years ago, letting officers search his house and volunteering for an interview without a lawyer. Smith has maintained his innocence since Parker's disappearance, his attorney told ABC News.

Orlando Police Chief Eric Smith, who is not related to the defendant, said investigators expanded the team over the past year and reexamined testimony and the suspect's conflicting statements, using advanced digital forensics to uncover and analyze additional evidence.

Detective Phillip McMican confirmed new evidence was collected in the past year and that technological advancements gave fresh insight into old evidence.

"Vehicles, electronic devices, phones, computers — we're able to better interpret that evidence today than what we were able to do back in 2011," McMican said. The chief did not disclose specifics, saying he did not want to compromise the prosecution.

On the same November 17, 2011 afternoon Parker vanished, a prerecorded episode of "The People's Court" featuring her and Smith aired, in which they settled a dispute over a $5,000 engagement ring Smith claimed she threw at him during an Atlanta hotel argument.

Judge Marilyn Milian found both at fault and ordered Parker to pay Smith $2,500 for half the ring. Her body has never been found.

Joshi said the defense is focused on filing a bond motion and working to get Smith released. Meanwhile, Orlando police continue to search for Parker's body, and investigators have not publicly stated a motive for her murder.

Detectives also noted that Smith gave different answers to the same specific questions when asked numerous times over the years, a detail Detective McMican highlighted in the briefing.

Chief Eric Smith, speaking at the news conference, said the case never stopped being a priority, and that "the things we couldn't do 15 years ago that we can do now allowed us to close this case."

With the defense signaling it will challenge the investigation's focus and the affidavit sealed, the pretrial phase will test whether decades-old digital evidence can carry a murder conviction without a recovered body.