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How the alleged bomber was caught

(CNN) DNA, fingerprints and pings from a cell phone tower led authorities to an auto parts store parking lot in south Florida where they arrested a 56-year-old man Friday morning. The arrest brought an end to a four-day nationwide manhunt for the alleged mailer of over a dozen suspected pipe bombs to prominent critics of President Donald Trump.

A key break in the case for investigators came Thursday, according to a criminal complaint and multiple law enforcement officials, when they traced five packages to the Opa-Locka processing and distribution center outside of Miami.

That break allowed authorities to narrow their search, which -- combined with DNA and fingerprint samples left on a package sent to Rep. Maxine Waters and cell phone geolocation information -- led to Cesar Sayoc, even as new devices were being found in New York and California.

FBI agents arrested Sayoc at an AutoZone parking lot in Plantation, Florida, about six miles west of Fort Lauderdale, Friday morning as he was nearing his white van, which has been covered with images political in nature, including images of notable liberals such as Hillary Clinton and former President Barack Obama.

A "CNN Sucks" sticker was also on the van. Two of the packages with explosive devices were addressed to the CNN New York bureau.

Other targets include former Vice President Joe Biden, and critics of Donald Trump including Waters, actor-director Robert De Niro, and Sens. Cory Booker and Kamala Harris. A suspicious package similar to the others this week was also found Friday in the San Francisco Bay area addressed to Democratic billionaire donor Tom Steyer.

Friday's arrest was the culmination of a multi-agency federal, state and local law enforcement and civilian effort that began Monday when the first suspected pipe bomb sent to George Soros, a billionaire philanthropist who has supported Democrats, was intercepted.

Three new suspected bombs were detected Friday morning in Florida, New York and California as agents in South Florida were preparing to apprehend Sayoc at the parking lot. The packages were nearly identical -- six inch PVC pipes with wires, stuffed inside a bubble-wrap lined manila envelope, according to the complaint. Six American flag stamps were affixed to each envelope with the return address of Florida Rep. Debbie Wasserman Schultz's office.

"These are not hoax devices," FBI Director Christopher Wray said at a news conference Friday.

Sayoc was charged with five criminal counts related to 13 explosive devices, Attorney General Jeff Sessions announced Friday. He faces up to 48 years in prison if convicted.

The investigation, led by the FBI and its Joint Terrorism Task Force, the NYPD, the US Postal Inspectors and other federal agencies and local law enforcement, depended heavily on the quick work of private security and US postal workers who detected bombs as they arrived at office buildings and post offices.

Authorities were also aided by mistakes made by the alleged bomber who left traces of evidence investigators scrambled to understand.

As explosive devices were sent to the FBI forensics lab in Quantico, investigators there detected DNA and a fingerprint found on the device intended for Waters and, working with local law enforcement, matched it late Thursday night to a sample of Sayoc's DNA that had been previously collected, Wray said.

Traces of DNA collected from two other of the bombs appeared related to Sayoc, according to the complaint filed in federal court Friday.

With his possible identity known, investigators checked his cell phone number against cell phone towers in the vicinity to see if they matched the location and timing for when the packages originated, according to a law enforcement official.

By Thursday night, agents and law enforcement officers, confident they had found the alleged bomber, were combing through social media posts of Sayoc and began surveilling him either Thursday night or Friday morning, the law enforcement official said.

Clues appeared to confirm their suspicions. Sayoc misspelled words on posts that matched some of those on the packages. Some posts said, "Hilary" instead of "Hillary" Clinton, while another said "Shultz" instead of Schultz for Debbie Wasserman Schultz.

Investigators first went to the home of Sayoc's mother in Aventura, but were told he wasn't there, according to a law enforcement official. As of Friday afternoon, authorities were searching his mother's residential complex.

Meanwhile, they detected a ping identifying Sayoc's cell phone. In the AutoZone parking lot, agents found the white van, where he appeared to be living.

Sayoc was initially somewhat cooperative, one official said. He told investigators that the pipe bombs wouldn't have hurt anyone and that he didn't want to hurt anyone. But he has since retained a lawyer so questioning has ceased. He is scheduled to appear in federal court on Monday in Florida.

Although Sayoc is in custody, FBI director Wray cautioned that there could be more potential explosive devices sent that have yet to be detected.

"Today's arrest does not mean we are all out of the woods," Wray told reporters. "There may be more packages in transit now."

Correction: This story has been updated to accurately state that the Joint Terrorism Task Force is run by the FBI.

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