John Evander Couey, a 47-year-old convicted sex offender, gave the confession to detectives, but also told them that he wanted to consult a lawyer. He wasn't given the opportunity to do so.
"This is a material and a profound violation of one of the most bedrock principles of criminal law," Circuit Judge Ric Howard said in issuing the ruling Friday.
Jessica was found kneeling and clutching a stuffed animal, hands tied with speaker wire and fingers poking through the garbage bags in which she was buried alive in February 2005. Two days earlier, Couey told detectives he had kidnapped, raped and killed the girl, and he told them where to find the body.
Prosecutors are seeking the death penalty for Couey, who has pleaded not guilty to charges of premeditated murder, burglary, kidnapping and sexual battery. Jury selection for his trial is expected to start July 10.
Couey and Jessica both lived in the Homosassa area. After Jessica disappeared, Couey fled the area as the search for the missing girl zeroed in on registered sex offenders in the area.
He was arrested in Georgia on an unrelated Florida warrant, and gave the confession in an Augusta, Georgia, sheriff's office to two detectives who traveled from Florida to interview him.
On the taped interview, parts of which were played in court, Couey spoke freely with the detectives about his criminal past, use of crack and relationship with his family. When the topic crept closer to Lunsford, however, Couey repeatedly mentioned wanting a lawyer.
Detectives Scott Grace and Gary Atchison have testified that Couey's mention of a lawyer came directly after Grace mentioned a polygraph test. They weren't sure if he wanted a lawyer immediately or for a later polygraph test, so they kept questioning after Couey said he would talk about "some things," Atchison testified.
Defense attorney Dan Lewan has portrayed the detectives as overzealous and unconcerned about Couey's constitutional rights. When his client asked for an attorney, Lewan argued, the detectives spoke over him in a confusing interlude before simply dropping the issue.
Lewan also asked the discovery of Jessica's body be inadmissible in court because Couey told authorities where to find her.
Prosecutor Ric Ridgway has said investigators would have found Jessica's body anyway.
A consent search at the mobile home where Couey was living turned up a bloody mattress which tested positive for Jessica's DNA the day they began excavating at the mobile home following the confession. Further, disturbed ground near a shovel in the yard was suspicious enough to investigate after officers had already singled Couey out as a person of interest, Ridgway said.
"With (DNA results) they would've gotten a search warrant for the home," Ridgway said.
Couey confessed to taking her from her house to the mobile home he was living in about 150 yards away, sexually assaulting and then burying the girl. Jessica had been missing for nearly a month before investigators found her body in the yard.
The case sparked new laws that dramatically stiffened penalties for some sex offenders who target children, requiring lifetime electronic monitoring for others.