Authorities know his name and where he lives and say it's only a matter of time before they bring him to justice, reports CBS News correspondent Terrell Brown.
But they're pursuing the suspect at a slower pace at the request of the State Attorney Bill Eddins, Escambia County Sheriff David Morgan told CBS' "The Early Show".
"We've been asked by the state attorney's office to coordinate any further steps in this process with them," Morgan said. "He's wanting to review the investigative file and make sure we effect this last arrest with a slower pace. I would not question the state attorney's reasoning for this. He has a plan."
Morgan said the slowed pace has nothing to do with lack of evidence, but is just a matter of Eddins exercising "good due diligence."
Seven other men are in custody Wednesday for the slays, which police say were motivated by robbery. Those arrested include an ex-convict who taught self-defense to children, a day laborer who served prison time for killing a man in a fight and an Air Force staff sergeant attached to an elite special operations unit.
Somehow, authorities say, they ended up part of a loosely connected group of seven men charged in the couple's shooting deaths.
The suspects, some dressed as ninjas, stole a safe and other items during the break-in Thursday at the sprawling Billings home west of Pensacola. Nine of the couple's 13 adopted children were home at the time. Three saw the intruders but were not hurt. Authorities would not say what was in the safe or what else was taken.
Some of the masked men entered through the front door, while others slipped in through an unlocked utility door in the back. They were in and out in under 10 minutes. The crime was captured by an extensive video surveillance system the Billings used to keep tabs on their many children.
Morgan said the team had been training for the robbery for at least a month.
"It was a very well-planned and well-executed operation," he said.
Morgan also told "The Early Show" that police have identified the "active shooter" in the murders, but declined to identify him.
The last three of the seven suspects were arrested Tuesday.
Adult daughter Ashley Markham - one of four Billings children from previous marriages - sobbed Tuesday as she hugged Morgan, who said he kept a promise made to her the night of the slayings.
"It is my honor today to tell you, Ashley, your family we have found them and they are in custody," Morgan said.
The suspects ranged in age from 16 to 56, and several were day laborers who knew each other through a pressure washing business and an auto detailer they worked for. One, Donnie Ray Stallworth, was with the Air Force Special Operations Command with an aircraft maintenance squadron at Hurlburt Field near Fort Walton Beach. It wasn't clear how he knew the others.
"We're dealing with a group of folks with rare exception - of course, there's a couple of people who are not - that again are basically day laborer sorts, folks that get odd jobs, part-time jobs and they drift," Morgan said. "With the exception of Mr. Stallworth you don't have any career-minded people in this group."
Morgan called 35-year-old suspect Leonard Gonzalez Jr. a "pivotal person" in organizing the crime, but stopped short of identifying him as the mastermind. He was charged Sunday with murder.
In court Tuesday, he read a statement proclaiming his innocence.
"The sheriff intentionally thrust me into the public's eye without any charges being filed and also intentionally placed me in a suicide ward to make me look even guiltier," Gonzalez said.
News clippings provided a very different picture of Gonzalez, a former National Guard member and martial arts expert who taught self-defense classes for women and children. In 2007, he and his wife founded a martial-arts course that taught children to defend themselves against sexual predators.
Gwinn Corley, a spokesman for a community group that gave Gonzalez and his wife an award for their program, said they brought their six young children to self-defense presentations.
"We were impressed with them," Corley said. "He was talking about children and their respect for their elders. They both seemed to have a passion to teaching the arts to abused women and kids, they had a vision for how to give free self defense."
But records show Gonzalez, who was arrested Sunday in the Billings case, served time in Florida State Prison on burglary and forgery charges in the mid-1990s.
His father, Leonard Gonzalez Sr., was also arrested. The 56-year-old was charged Sunday night with evidence tampering after authorities said he tried to cover up some damage on a red van seen on surveillance video pulling away from the house. Officials said the damage was unrelated to the crime. Tips from the public led police to the van Saturday.
The elder Gonzalez owned a pressure washing business and may have visited the Billings property once before. Another man arrested and charged with murder Sunday, day laborer Wayne Coldiron, 41, sometimes worked for him and also may have visited the property, Morgan said.
Coldiron, who appeared in court Tuesday and said he had lost his job as a plumber, served two years in a Tennessee prison in the early 1990s after killing a man during a fight. He also served nearly two years in prison in Florida on an aggravated assault charge.
The other four suspects were arrested Monday and Tuesday.
Authorities in neighboring Okaloosa County arrested 31-year-old Gary Sumner, another day laborer who was in a county jail on an unrelated traffic charge. On Tuesday, three more men were arrested: Stallworth, 19-year-old Frederick Lee Thornton, and a 16-year-old whom officials are not naming because he is a minor.
Eddins, the prosecutor, said he would seek first-degree murder indictments from a grand jury against all the suspects, including Gonzalez Sr. He would not say whether he will seek the death penalty.
Escambia County Judge Tom Johnson refused to set bail for the younger Gonzalez and Coldiron at the request of Eddins. Johnson set their arraignments for Aug. 6. Bond for the elder Gonzalez had already been set at $500,000. The suspects arrested Monday and Tuesday are due in court this week except for Stallworth, who must be extradited from Alabama, where he was arrested.
The Billings family attended the hearing Tuesday but made no statements. Some were in tears afterward.
Friends, meanwhile, struggled to understand how the couple could have been killed in such a horrific way.
"Melanie and Byrd both would give you the shirt off their back and maybe they were too trusting," said Patsy Brown, who had known Melanie Billings for 22 years.