Political mail bomb passed through Opa-locka postal facility. But who sent it?

A sprawling U.S. mail sorting facility near the Opa-locka airport — the size of five football fields — took center stage Thursday when federal investigators discovered that at least one of the bomb-filled packages targeting an array of Democratic figures passed through the location.

Where that package originated, however, remained unclear because the Opa-locka postal facility sorts hundreds of thousands of packages daily that come in and out of South Florida. The bigger mystery was who plotted the series of mailings and why.

The package in question is likely the one that ended up Wednesday at the Sunrise congressional office of U.S. Rep. Debbie Wasserman Schultz, according to a federal law enforcement official familiar with the probe.

That package was originally sent to the office of former U.S. Attorney General Eric Holder in the Washington, D.C., area, but it did not get delivered and was sent back to the return address, which was listed as the congresswoman’s office in Sunrise. Before it got there, it was rerouted through the giant Opa-locka mail sorting facility, the official said.

That development capped a frenetic day for the FBI-led counter-terrorism team leading a nationwide search. The packages containing crudely fashioned devices that looked like pipe bombs have now been recovered in South Florida, New York , the Washington, D.C., area, California and Delaware. They were sent to at least 10 prominent Democratic politicians and other vocal critics of President Donald Trump from presidential nominee Hillary Clinton to actor Robert De Niro.

The U.S Postal Service directed investigators to Opa-locka after reviews of mail scans showed some of the devices had found their way through the massive sorting facility.

On Friday, the FBI confirmed that an 11th package, similar in appearance to the others, was “recovered in Florida” and addressed to Sen. Cory Booker of New Jersey. But in the brief news update, the agency did not say whether the manila envelope, which also listed Wasserman Schultz on the return address, was processed at the Opa-locka mail facility.

It was also reported that a 12th package, addressed to James R. Clapper Jr., the former director of national intelligence, was intercepted at a New York City mail facility. The package was addressed to Clapper at CNN’s news offices in New York.

The bombing devices — clearly aiming to shake up the political landscape just two weeks before the midterm elections — were so poorly constructed that at least one source involved in the investigation told The Miami Herald that they could not detonate. Whether they were intentionally designed that way was not known.

After news media reported on the Opa-locka mail facility’s connection to the bomb threats late Thursday, the Miami-Dade County Police Department dispatched a bomb squad and K-9 unit to do a sweep of the place. No explosive devices were found.

U.S. postal inspectors in Florida and the other states are combing databases to see if there are any other suspicious packages en route to more potential political targets.

The South Florida connection was just the latest development in a widening probe into the threatening mailings.

The White House has condemned the attacks, with Trump saying “acts or threats of political violence have no place in the United States.”

Three more packages containing similar devices were found as well, the FBI confirmed on Thursday. Two were sent to Joe Biden, the former vice president, who lives in Delaware. Another targeted De Niro, who lives in New York City. The Oscar-winning actor has been outspoken in his disdain for Trump, calling him the “baby-in-chief” and other derisive terms.

Because of their similarities — all of the packages had the Sunrise office of Wasserman Schultz as a return address — investigators believe the mailings were likely the work of one person or one group.

The FBI’s assistant director, William Sweeney, declined to say where the packages originated. “I’m not going to get into specifics where the packages came from,” Sweeney said during a Thursday afternoon press conference in New York.

Investigators were also analyzing the devices, which resembled pipe bombs, to see if they were rigged to actually explode.

“The way they were constructed they were not going to go off,” one law enforcement official told the Herald. “You could not compare them to the Boston Marathon bomber.”

But at a news conference in New York City, police commissioner James O’Neill cautioned against dismissing them as hoaxes, calling them “live devices.”

The bombs, made from PVC pipe and covered with black tape, were about six inches long and packed with powder and broken glass, said a law enforcement official who viewed X-ray images and spoke on condition of anonymity, according to the Associated Press. The explosive devices also contained a small battery.

While the investigation found at least some of the packages were processed in the Opa-locka facility, it doesn’t necessarily mean that they were manufactured in or mailed from South Florida. Hundreds of thousands of packages pour in daily. The facility handles packages mailed in South Florida from Monroe County to Palm Beach County but also receives packages from across the nation. International shipments, however, are processed at a separate facility in Doral.

There also are no retail services at the sorting facility — customers cannot walk in and buy stamps, send a package or check a P.O. box. The facility, online anyway, is also the ire of the online commentators who have long complained their packages vanish in the “black hole” of the operation.

Miami Herald staff writers Douglas Hanks and Charles Rabin contributed to this story, which was supplemented with wire reports.

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