Seven men are jailed on charges including murder, in the shooting deaths of Byrd and Melanie Billings, who had 17 children -- four biological and 13 adopted.
Escambia County Sheriff David Morgan told CBS "Early Show" on Wednesday that investigators had "verified yesterday that this team, this group of people, had been in training at least 30 days, a month, prior to the execution of it at the Billings' compound."
Morgan said investigators believe they know who shot the couple but he declined to give more details.
The break-in was captured by an extensive video surveillance system used by the couple to keep tabs on their children.
Surveillance video showed three armed, masked men arriving in a red van, entering through the front of the house and then returning to the vehicle. Others dressed in what the sheriff called "ninja garb" went in through an unlocked utility door in the back. They were apparently in and out in under 10 minutes.
Several of the suspects were day laborers who knew each other through either a pressure-washing business or a car detailing group, Morgan said.
Nine children were at the Billings' home when the couple was killed. Byrd and Melanie Billings owned several local businesses, including a finance company and a used-car dealership.
PREVIOUSLY ON CRIMESIDER
July 14, 2009 - Faces of Evil? 7 in Custody in Slaying of Wealthy Fla. Couple
July 14, 2009 - Fla. Couple Killed: What Horrors Did Children Witness?
July 13, 2009 - Parents to 16 Slain for Nothing
July 10, 2009 - Parents of Sixteen Slain