TAMPA — Just a day after double killings left the highly secure Avila enclave in northern Hillsborough County astounded, investigators announced the arrest of the man they say called 911 and pretended to be a victim himself: Julian Ospina-Florez, 31, of Tampa.At a news conference late Tuesday, Sheriff David Gee said Ospina-Florez was responsible for the deaths of retired physician Hector Rivera, 76, and his wife, Debra Rivera, 55.The sheriff said the suspect owned a 9mm handgun that was found tucked in a drawer in the mansion and had purchased ammunition last month at a Walmart.Debra Rivera worked from home, selling jewelry, handbags and accessories. Ospina-Florez worked for her company, Distinctive Creations, for a year as an assistant and a driver, Gee said. But she recently had a falling out with him.Gee hinted that Ospina-Florez, originally from Medellin, Colombia, might be responsible for a burglary at the home this month."It was a very brutal killing," Gee said. "He was definitely making sure that no one was leaving that residence."Investigators had spent hours reviewing security video, checking guest logs and scouring a lake. But they knew that unless someone had scaled Avila's 8-foot perimeter wall, the killer's entrance was recorded.Residents get in to the exclusive community with a barcode on their vehicle. Visitors must be invited and pass through a guarded gate.Authorities said they determined that, minutes after Ospina-Florez drove Debra home from a Sarasota trade show Monday night, he shot her several times while she was in a bathroom. When her husband came walking up the drive from watching a football game at a neighbor's, with a plate of food for her, the driver shot him, too, officials said.Ospina-Florez was booked late Tuesday on two counts of premeditated first-degree murder and was being held this morning without bail at the Hillsborough County jail. Investigators were searching the townhome he owns at 11718 W Wesson Circle near Carrollwood.The slain couple's son, Hector Rivera Jr., 33, and his wife said they were too distraught to talk Tuesday. They were also afraid. Police guarded the couple's South Tampa house at their request.• • • Avila is a neighborhood so secure that some of its wealthy residents keep their doors unlocked. But just before 8 p.m. Monday, gunshots echoed through the community.The couple's home where a deputy discovered the bodies Monday night, at 814 Taray De Avila, is nearly 7,000 square feet in two stories, contains six bathrooms and four bedrooms and is assessed at more than $1 million, according to the Hillsborough County property appraiser.Several neighbors heard the gunfire.One neighbor was tucking his daughter into bed. He ran downstairs to check. Another spotted sheriff's cars and walked outside, but was told by a deputy to get back inside the home.Deputies recorded the identification of each driver leaving Avila and blocked off the street where the Riveras lived.The homeowners association sent emails to residents, asking them to stay inside and lock their doors. Avila's security guards helped detectives review surveillance footage until 5 a.m.Someone had reported a burglary at the Rivera house earlier this month. Gee said Debra had a growing mistrust of Ospina-Florez, and pointed to that burglary as a possible reason.The stolen items included several large storage bins and photocopiers and typewriters, valued at $256. Gee said Debra said some jewelry was missing as well. The sheriff noted the burglary was still under investigation.But he wondered if she had asked Ospina-Florez that day about the missing jewelry."It would be speculation," Gee said, "but we know he was not in good standing with her."• • •Just before 8 p.m. Monday, the Sheriff's Office took a call about shots being fired near the home. Then a second call came in.It was from Ospina-Florez, the sheriff said, calling 911 from inside the mansion.Under questioning, the Sheriff's Office said, Ospina-Florez asserted that an unknown man had burst into the home and attacked him — tying him up and forcing him into a bathroom.But investigators said Ospina-Florez was uninjured, and they saw no clues of a forced entry.Instead, authorities said, they found a gun in the home that was owned by him, and ammunition that matched in his car outside.As the case is presented to a grand jury over the next few weeks, Gee predicted, "There is a lot more physical evidence that will come out."Records show that the only previous criminal past in the state for Ospina-Florez was in 2004, when he was arrested in Hillsborough on a misdemeanor battery charge and a felony burglary charge. Details of the incident were not immediately available, but prosecutors later dropped the case.Ospina-Florez became a naturalized U.S. citizen about a decade ago, Gee said.•••Dr. Rivera was a well-known physician whose Town 'N Country practice dates to the 1960s. He was the go-to doctor in west Hillsborough back then, said Barbara Fonte Flannery, 59. He would make house calls at odd hours, and if Flannery's father didn't have the money, it was no problem."Pay me when you can," the doctor would say.Debra was the office manager, and the pair quickly became infatuated with each other, friends say. Some colleagues at Town 'N Country Hospital were wary because she was 20 years his junior. But as soon as they met Debra, they were smitten."She was so charming, so bright and smart and beautiful," said Christy McLaughlin, who was married to a Town 'N Country doctor at the time. "The men were all crazy for her."Hector was just as personable. He would hug acquaintances and mentor young doctors.During a dinner at Bern's Steak House about 20 years ago, he gave medical care to a young woman who had fallen unconscious, helping her until paramedics arrived."Everybody knows them. They've been in Tampa all their lives," said a nephew, Alex Rivera. "My aunt and uncle are as normal as it gets."Over the years, the couple assembled a list of prominent friends. Former Tampa Bay Rays manager Lou Piniella said Tuesday that he was too upset to talk. Dr. Ruben Valdes, a friend of Hector's for 40 years, said Hector was getting bored with retirement and wanted to start working again, part-time. The two had made plans to play golf later this week."I don't know if he had any enemies or anything," said Valdes, 68. "I just don't understand why this happened."Times staff writers Danny Valentine, Marissa Lang and Amy Scherzer and researcher John Martin contributed to this report. Jessica Vander Velde can be reached at (813) 226-3433.