USF confirmed the man who placed an improvised explosive device outside the MacDill Air Force Base was enrolled at the university until this spring. SPECIAL TO THE ORACLE/WIKIMEDIA COMMONS

A former USF student was indicted Wednesday on three counts tied to an improvised explosive device outside the MacDill Air Force Base in Tampa.

On March 10, Alen Zheng attempted to detonate an improvised explosive device at the MacDill Air Force Base visitor’s center, according to the indictment unsealed by the U.S. Department of Justice Thursday.

A MacDill Air Force serviceman found the improvised explosive device on March 16, which resulted in a six-hour closure of the Dale Mabry gate and visitor center, according to its Facebook.

MacDill spans nearly 6,000 acres in South Tampa and is a hub for military operations, including the headquarters of the U.S. Central Command and Special Operations Command, according to its website.

Alen Zheng, 20, faces charges of attempted damage of government property by fire or explosion, unlawful making of a destructive device and possession of an unregistered destructive device, according to court records.

His sister, Ann Mary Zheng, 27, was indicted Thursday with accessory after the fact and evidence tampering, according to a DOJ press release.

If convicted, Alen Zheng could face five to 40 years in federal prison, while Ann Mary could serve up to 30, according to the DOJ.

An indictment is a formal charge issued by a grand jury of one or more violations of federal criminal law, and does not mean a defendant is guilty, according to the DOJ.

USF spokesperson Adam Freeman confirmed Alen Zheng was enrolled at the university and majored in accounting from summer 2024 to fall 2025, and withdrew this spring.

Freeman said the university has no records of Ann Mary Zheng attending USF.

“The university is aware of the situation,” Freeman said. “The safety of students, faculty and staff is always our highest priority.”

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Gregory Kehoe, a U.S. attorney for the Middle District of Florida, said law enforcement received a 911 call on March 10 about the improvised explosive device being placed at the MacDill Air Force Base in a Thursday press conference.

Kehoe said base personnel searched the entire base, but did not find the device until March 16. 

While the device did not detonate, Kehoe said the explosive could have been “very deadly.”

Kehoe said Alen Zheng and Ann Mary Zheng sold the car used to transport the device to the base and bought plane tickets to China on March 11, a day after the attempted detonation.

On March 12, the two departed for China from Tampa International Airport, though Ann Mary returned to the U.S. in Detroit, Michigan, on March 17. Ann Mary’s reason for returning is still unknown, Kehoe said.

A federal marshal booked Ann Mary Zheng into the Pinellas County Jail on Wednesday at 6 p.m. and released her to U.S. marshals Thursday morning, according to the Pinellas County Sheriff’s Office charge report.

Kehoe said Alen Zheng is still in China, adding that U.S. officials are working to bring him back to the U.S.

“We’re exploring every avenue we can to get him back to the United States,” Kehoe said.

The U.S. and China do not have an extradition treaty — which returns suspects for crimes committed in either country — but negotiate individual cases, according to the DOJ.

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FBI special agent in charge Matthew Fodor said agents removed the device on March 16 and transported it to the FBI’s Terrorist Explosive Device Analytical Center in Huntsville, Alabama for testing.

“It was only a matter of hours that we had viable information that eventually led us to indictments of Alen Zheng and his sister Ann Mary,” Fodor said.

Kehoe said that agents pinpointed the International Mobile Equipment Identity for the phone used in the 911 call in less than 24 hours after finding the device.

An International Mobile Equipment Identity is a unique 15-digit number assigned to each mobile device, according to T-Mobile. Carriers and law enforcement use these numbers to identify, track and sometimes block stolen or lost phones.

Kehoe said investigators traced the 911 call to a phone Alen Zheng had recently purchased at Best Buy, and confirmed this through store surveillance footage.

He said the FBI obtained warrants to search the Zhengs’ home in Land O’ Lakes and found improvised explosive device parts similar to the one found outside the base.

Both Ann Mary Zheng and their mother told investigators Alen had admitted to building and placing the device at the military base.

Their mother is currently in U.S. Immigration and Customs Enforcement custody, but has not been connected as a defendant in the case, Kehoe said. 

Still, Kehoe said the investigation is ongoing and will work to serve justice to everyone involved.

“If you threaten to harm somebody or if you harm somebody in the Middle District of Florida, you will be brought to task,” Kehoe said. “You will be brought to book and you will be charged.”