"We will be representing him zealously, and the next step we will take is to enter a plea of not guilty on his behalf," he said.
As police tell it, Hadley posted word on Facebook around 1:15 p.m. Saturday that he would be hosting a party at his house that night. Sometime afterward, the parents were attacked outside their bedroom, where their bodies were brought and covered with varied household items, and the door was locked.
The party went on as planned, with as many as 60 guests having such a raucous time that police were called with a noise complaint. They arrived at about 1:30 a.m. Sunday, but the party was already breaking up.
Then, tipped off that a murder may have taken place, they returned to the home at about 4:24 a.m. Hadley was seen pacing inside a front bay window, police said, and when he finally answered the door he appeared nervous.
Inside the master bedroom, they found the bodies.
Police would not say who called in the tip about a possible slaying, how the person knew or how the person was connected to the family.
Since his arrest, Hadley has been questioned by police, but has given no inkling what motivated his alleged actions, said Tom Nichols, a police spokesman in Port St. Lucie, which is about 50 miles north of West Palm Beach.
"He didn't say anything as to why this murder occurred," Nichols said.
The mother, 47, was an elementary school teacher. The father, 54, worked for Florida Power and Light. The Hadleys also had a 23-year-old son who lives out of state. Relatives of the family declined to comment or let calls go unanswered.
As police probed for clues, so did those who knew the family.
"They always seemed happy," said James Moses, another neighbor. "There was no indication that anyone was dysfunctional."
Associated Press writer Suzette Laboy in Miami contributed to this report.