Brother and sister are charged after an explosive device was found outside a Florida Air Force base

The U.S. Central Command at MacDill Air Force Base is seen, Feb. 6, 2017, in Tampa, Fla. (AP Photo/Susan Walsh, File) Updated [hour]:[minute] [AMPM] [timezone], [monthFull] [day], [year] FORT LAUDERDALE, Fla. (AP) — A man who fled to China after leaving an explosive device outside MacDill Air Force Base in Tampa has been indicted along with his sister in Florida on federal charges, and their mother has been detained pending deportation for overstaying her visa, a federal prosecutor said Thursday.Alen Zheng, 20, and Ann Mary Zheng, 27, were charged Wednesday in separate federal indictments. The sister was arrested upon her return from China, where she had flown with her brother after the threat. Both have U.S. citizenship, U.S. Attorney Gregory Kehoe said during a news conference.The device didn’t detonate, but “could have potentially been very deadly,” Kehoe said.Alen Zheng faces 40 years in prison if convicted of attempting to damage government property and unlawfully making and possessing the explosive device. Ann Mary Zheng faces 30 years if found guilty of witness tampering and being an accessory after the fact to the crime, by allegedly selling the car he used to drop off the package, Kehoe said. A federal public defender declined to comment on the charges against the siblings. The suspicious package went undiscovered for nearly a week, but the investigation developed very quickly after it was found on March 16, Kehoe said.Agents determined that Alen Zheng actually planted the device on March 10 and made a 911 call minutes later saying there was a bomb at the base, he said. Then he and his sister sold their Mercedes-Benz SUV, bought tickets to China, and were gone by March 12th. Air Force personnel had searched the sprawling base without discovering the device initially. When it was found outside the visitors center, investigators kicked into high gear. They used phone data to connect the 911 call to Alen Zheng, and spotted the SUV on surveillance video. By the time they reached CarMax, the car had been vacuumed and cleaned, but they were still able to find evidence including residue matching the explosive, Kehoe said. Agents also searched the family’s home and reported finding explosive device components. Meanwhile, the device found outside the base’s gate was flown by helicopter to an FBI lab in Huntsville, Alabama, for further examination, FBI Special Agent in Charge Matthew Fodor said.Kehoe said he’s not sure if the siblings also have Chinese citizenship. He said they have no immediate evidence that Alen Zheng was working on behalf of the Chinese government or any other country. “We’re exploring every avenue we can to get him back to the United States,” Kehoe said.The U.S. Central Command is located at MacDill and is responsible for U.S. military operations in the Middle East, Central Asia and parts of South Asia. MacDill is one of the U.S. bases that has been on heightened alert since the war in Iran began.Another man was arrested earlier this week on charges of making threatening phone calls to the base days after the device was discovered, though investigators haven’t accused that caller of planting any devices. There was no immediate connection between that caller and the Zhengs.