Hillsborough County Sheriff's Col. Donna Lusczynski said at a news conference Friday that Darrin Campbell had purchased fireworks, gas cans and gasoline in the days before the family was killed.
Campbell shot his wife, Kimberly, 19-year-old son Colin and teenage daughter Megan each in the head with a .40-caliber handgun he bought last year before setting the house on fire and shooting himself in the head.
"This is certainly disturbing," Lusczynski said.
Investigators are still working to determine what drove Campbell to kill his family.
Lusczynski said the sheriff's office had not been investigating Campbell before the killings and did not know of any other agencies that may have been investigating him. Campbell had no criminal record before his death.
Investigators are looking into the family's finances and going through records found in the home, Lusczynski said.
The Campbells had been renting the 6,000-square-foot house from James Blake, a former professional tennis player. The million-dollar home was located in Avila, a gated community known for its resident sports stars and CEOs. Located on one of Tampa's most exclusive streets, in one of its most secure, tony neighborhoods, the five-bedroom, five-bath home had a pool and spa, and was graced by tall palm trees.
Campbell had been an executive for several high-profile businesses, including a stint at PODS, the mobile storage company. He was most recently working at a records-management firm and volunteering as treasurer at his children's private school. Kimberly Campbell was a stay-at-home mom, according to her father, Gordon Lambie.