Wiggins, 47, was the eighth person arrested in the crime that shocked the nation because the couple had become well known for adopting children with special needs. She was found on her yacht, the Classy Lady, in Alabama on Wednesday. She also owns a dozen properties in three states and a Rolls Royce.
Several weapons were recovered Thursday, Eddins said, including the probable "murder weapon or weapons." It was not immediately clear from where investigators recovered the weapons. Police have enlisted the help of the federal Alcohol, Tobacco and Firearms to test the weapons for prints, DNA, blood splatters and ballistics, Morgan said.
Morgan speculated that murder may not have been the alleged robbers' original intention, likening the double murder to a drug deal gone bad.
"There was never any mayhem or murder in the intent there" until something went wrong, he said. "It's hard to say unless you're in the psyche of the criminal."
Morgan confirmed reports that the Drug Enforcement Agency was helping in the investigation, but he refused to spell out their role other than to say the DEA was investigating the suspects.
"Look at it from a broad perspective," DEA spokesman David Melenkevitz told ABCNews.com. For the sheriff's office to call in the DEA, "There has to be some drug connection somewhere."
Melenkevitz would not elaborate on the DEA's investigation.
Nine of the Billings' children were in the home when their parents were killed.
The Associated Press contributed to this report.