PENSACOLA, Florida (CNN) -- Thousands paid their respects Thursday to a Florida couple slain during what police said was a home invasion robbery.
Byrd and Melanie Billings did not have any children together, but they cared for 16 children over the years.
The bodies of Byrd and Melanie Billings arrived at Liberty Church in separate hearses for the service, the first of two planned for the couple. The funeral will be held Friday.
Those attending looked at pictures of the family on posters and video monitors in the church lobby during the somber gathering. A constant stream of cars arrived and departed during the three-hour service. The Billingses' caskets were closed.
Seven men -- one of them a 16-year-old -- are charged with murder in the killings. An eighth person, Pamela Long Wiggins, faces charges of accessory after the fact of felony murder.
Authorities located "valuable evidence," including a stolen safe and several guns, in the investigation into the slaying of a Florida couple, state attorney Bill Eddins said Thursday.
Authorities believe at least one of those guns was used to kill Byrd and Melanie Billings, he said.
The couple, known for adopting special-needs children, were shot to death last week in their Beulah, Florida, home, near the Alabama border. Their funerals will be held Friday.
"In our opinion this was a home invasion-robbery where the people stole a safe and we recovered the safe," Eddins told reporters at a news conference. "I personally ... think it is as simple as that in terms of the motive and what occurred."
He did not say what the safe contained or where it was found. But Sheriff David Morgan of Escambia County, Florida, told CNN the safe was found at a property that Wiggins' husband said belongs to the couple. Morgan gave no further details. Watch news conference detailing the findings »
He declined to say how many guns were recovered, but said "it would be a safe assumption" that the number of weapons was about the same as the number of suspects in the killings.
The federal Bureau of Alcohol, Tobacco, Firearms and Explosives said at least some of the weapons would undergo ballistics testing at its Atlanta, Georgia facility. A federal law enforcement source told CNN some weapons, but not all, were already at the ATF facility as of Thursday night.
Deputy Christopher Welborn of the Escambia County Sheriff's office said Wiggins, whom authorities have described as a landlord and friend to one of the suspects, has been freed on a $10,000 bond.
Morgan, speaking at the same news conference as Eddins, said authorities do not believe that anything else is missing from the Billingses' home. He said Thursday that authorities are still looking to interview additional people to "put the case finally to bed." Watch expressions of relief after arrests »
Surveillance video taken from the couple's home shows two vehicles pulling up to the property and five people, masked and dressed in black, entering the house. Authorities believe both drivers remained in the vehicles.
Morgan said earlier this week that it appears the suspects did not believe they were under surveillance, and he has pointed to the fact that the system was not disabled as a "gaping hole" in a well-executed crime. Watch sheriff describe crimes »
The sheriff also addressed at the news conference the role of the Drug Enforcement Administration in the investigation, reading a statement from the agency saying it is providing "investigative assistance at the request of the Escambia County Sheriff's office."
"No additional information is being provided at this time," he read. "The DEA was called in on the suspects in this crime, to assist us in that area," he explained.
The Billingses at one time had 13 adopted children, many with special needs. Three of those children died over the years. Byrd and Melanie Billings also each had two biological children of their own, but no biological children together. Watch surveillance video of the home invasion »
Nine of the couple's children were home at the time of the incident, authorities said, and police believe three of them saw the intruders. One managed to flee the home and seek help at a neighbor's house, authorities said.
Leonard Patrick Gonzalez Jr., one of the suspects, appeared in court Wednesday and read a statement proclaiming his innocence.
"The state's entire case is based on hearsay and circumstantial evidence," he said via video.
Authorities have said that Wiggins is Gonzalez's landlord and family friend. They have described Gonzalez as the organizer of the crime.
Gonzalez's father, Leonard Patrick Gonzalez Sr., 56, is also charged. Others charged in the case are Gary Lamont Sumner, 30; Fredrick Lee Thornton, 19; Wayne Thomas Coldiron, 41; Donald Ray Stallworth, 28; and a 16-year-old whom authorities have not identified.
CNN's Ed Lavandera, Susan Candiotti and John Couwels contributed to this report.