By Elizabeth Weise, USA TODAY  SAN FRANCISCO  After coming all the way from Estonia, Georg Merilo and his 4-year-old son Franc weren't worried about visiting the zoo in which a tiger killed one young man and injured two others on Christmas Day.  To Merilo's mind, it was the humans who were likely the problem, not the tigers. "People are the same everywhere," he said. "We have a zoo in Tallinn (Estonia's capital), and there's always someone who puts their glove too close to the monkey cage, and the monkeys grab it."  That was a common observation of the patrons who braved an incoming Pacific storm and a crowd of reporters, photographers and TV cameras for the 10 a.m. reopening of the San Francisco Zoo.  The zoo closed nine days ago after a tiger killed Carlos Sousa, 17, and seriously injured his two friends. Police shot the 350-pound Siberian tiger, Tatiana, as she came toward them.  As patrons came in, many stopped at an impromptu memorial that sprang up for both Sousa and Tatiana at a bronze tiger statue just inside the zoo entrance. Normally, children climb on the statue to have their picture taken. On Thursday, visitor after visitor dropped off flowers, stuffed toy tigers, cards and photos of Tatiana.  "There are only so many of them in the world," Nathaniel Todd, 14, said of Siberian tigers. "I've visited the tigers here many times," said Todd, who has been a volunteer at the zoo for two years.  He left a photo he'd taken of Tatiana and a note praising the San Francisco zookeepers and animal care staff.  Inside the zoo were a new public alert system and signs warning visitors not to harass the animals. A phone number was posted to enable witnesses to "immediately" report anyone doing so.  At the Lion House, home to the zoo's lions and tigers, workmen were already busy with jackhammers in the outdoor grottos. Zoo officials have promised that a more secure enclosure with a 19-foot barrier will be up within 30 days. The Lion House will remain closed until then.  Sousa was killed, and brothers Kulbir Dhaliwal, 23, and Paul Dhaliwal, 19, were severely injured. A year before, the same tiger gnawed on the arm of her keeper during a feeding.  A number of questions still surround the attack. Was the tiger provoked? Did the zoo realize the wall around the tiger grotto was too low? The wall was 12 feet; the Association of Zoos and Aquariums recommends 16½ feet.  "Something happened to provoke that tiger to leap out of her exhibit," zoo Director Manuel Mollinedo said.  Police investigators found an empty vodka bottle in the car that the young men drove to the zoo, San Francisco police Sgt. Steve Mannina said. Toxicology tests on Sousa's body will take weeks, the San Francisco Medical Examiner's office said.  Zoo employees found branches, pine cones and at least one 9-inch rock in the tiger grotto after the attack. None could have gotten in on their own, said the zoo's public relations coordinator, Sam Singer.  "They would have had to be thrown in," he said.  A police investigation is on-going, Singer said. "Something unusual happened on Christmas Day 2007 that changed a normally safe situation and made it a tragic one," he said.  The injured brothers are being represented by high-profile attorney Mark Geragos. According to his website, Los Angeles-based Geragos has represented actress Winona Ryder, pop star Michael Jackson and Scott Peterson, convicted of killing his pregnant wife, Laci.  Geragos says that the victims did nothing to harass the tiger.  Conversation guidelines: USA TODAY welcomes your thoughts, stories and information related to this article. Please stay on topic and be respectful of others. Keep the conversation appropriate for interested readers across the map.
Nine days after a tiger mauled three visitors, the San Francisco Zoo reopened Thursday amid heightened scrutiny of its security procedures and a flurry of questions over the events that led to a teenager's death.