On Twitter, Cesar Sayoc Jr. lashed out at immigrants, gun control advocates, and prominent Democratic politicians.

On Facebook, he misspelled a racial epithet, directing it at the likes of Oprah Winfrey and former president Barack Obama.

With fury in his fingers, he shared inflammatory news stories from Breitbart, hard-edge videos from Fox News, and angry posts from pages like “Handcuffs for Hillary.”

He tweeted a threat to former Vice President Joe Biden. And he posted photographs of himself wearing a red “Make America Great Again” hat at one of President Donald Trump’s campaign rallies.

After a frenzied nationwide search for the person who sent more than a dozen makeshift bombs to some of Mr Trump’s most prominent critics, Mr Sayoc, 56, was arrested Friday morning (local time) in Plantation, Florida, at an AutoZone car parts shop.

Authorities released a photograph of a man with a buzz cut and a mouth that drooped toward a frown. They hauled away a white van plastered with bombastic stickers expressing support for Mr Trump and animosity toward those who clashed with him.

“Dishonest Media,” read one on the van’s back right window. “CNN Sucks.” Crosshairs appeared on a photograph of one of the liberal commentators at the network, which received more than one package from Mr Sayoc at its offices in New York.

Records show he was a registered Republican; friends said he once danced as a male stripper. He also had a lengthy criminal history – he was once accused of threatening to use a bomb against a customer service representative – and led a life filled with failure.

Well into middle age, he was living with his mother with no furniture, according to 2012 bankruptcy records, and he appeared to have been living most recently out of his van.

Federal officials said Friday they were still exploring questions of motive.

“He appears to be a partisan,” Attorney General Jeff Sessions said at an afternoon news conference announcing Mr Sayoc’s arrest, “but that will be determined by the facts as the case goes forward”.

And so, even as the details of a grim and bitter life began to emerge Friday, a shaken country was left to ponder what could have prompted someone full of political grievances to manufacture a slew of improvised explosive devices.

Some of the packages falsely listed as a sender Representative Debbie Wasserman Schultz. On Friday, Ms Schultz spoke, with a shaking voice, for the first time about the ordeal.

“No matter what your political persuasion, we need to turn the volume down,” she said. “It’s deeply disturbing. I just can’t imagine that anyone would do this.”

On Monday, law enforcement officials discovered the first package linked to Mr Sayoc at a private home outside New York City that belongs to George Soros, the billionaire philanthropist. Days later, Mr Sayoc would post tweets that targeted Mr Soros and others, according to the criminal complaint.

Mr Sayoc’s posts on various social media accounts in 2015 showed an obsession with workouts and night life promotion, with little to no political content. But his more recent posts are full of political rage. His Facebook account, widely pored over after media reports of his arrest, suddenly disappeared Friday.

“We have found and immediately removed the suspect’s accounts on Facebook and Instagram,” Facebook said in a statement. “We will also continue to remove content that praises or supports the bombing attempt or the suspect as soon as we’re aware.”

Much remains opaque about Mr Sayoc. Some of his social media posts seemed to suggest he was part of the Seminole tribe in Florida. But Lenny Altieri, a relative, said that Mr Sayoc’s father was from the Philippines and his mother was from Brooklyn. He was raised by grandparents after having problems with his mother, Mr Altieri said.

Mr Sayoc had short stints in college as a young man, and had a passion for soccer, reflected in numerous soccer-themed messages on the van.

He attended Brevard College, a small, Methodist-affiliated liberal arts college in western North Carolina, for a year beginning in the fall of 1980 and played on the soccer team but did not graduate, according to a spokeswoman. He also attended University of North Carolina at Charlotte for one year starting in 1983, an official there said.

Back in Florida, Mr Altieri said, Mr Sayoc was obsessed with bodybuilding and worked as a male stripper. He also worked as a manager for traveling “male revue shows,” said Rachel Humberger, the wife of one of Mr Sayoc’s business partners.

Ms Humberger said that Mr Sayoc seemed like a friendly man, based on the short interactions she had with him, and described the shows as “Magic Mike style,” a reference to a 2012 movie about male strippers, Magic Mike.

More recently, she said Mr Sayoc had been talking to her husband about starting a new business: fish farms.

Altieri said that Mr Sayoc at one point had “a lot of money, but lost most of it”. He did not elaborate on how Mr Sayoc had acquired it.

Mr Sayoc amassed a lengthy criminal record, dating back to 1991, which includes felony theft, drug charges and fraud, public records show.

In August 2002, Mr Sayoc, in a dispute with a power company over a bill, was accused of threatening to blow up the company. Mr Sayoc was on the phone with the customer service representative and “was upset over an amount that he was being billed for”, according to records released by the Miami-Dade State Attorney’s Office. He “then stated that he didn’t deserve it and that he was going to blow up” the utility.

The customer service representative pressed an emergency button, which began recording the conversation. Mr Sayoc stated that what he planned would be worse “than 9/11” and that he planned to blow the agent’s head off, according to the records.

When the agent said Mr Sayoc did not want to be making such threats, prosecutors said he had replied “that he doesn’t make threats, he makes promises.” Mr Sayoc later described his remarks as nothing more than a joke.

In June 2012, Mr Sayoc filed for personal bankruptcy, listing assets of $US4175 ($5887) and liabilities of $US21,109 ($29,770).

“Lives w/mom,” a handwritten note on the petition said. “Has no furniture.”

A later place of residence was the white van, which he often parked outside an ageing strip mall in Aventura, Florida, that houses an LA Fitness, a Jewish market, a bakery and a post office.

Manuel Prado, a 56-year-old hairdresser in a salon at the mall, Shoppes at the Waterways, said he had seen Mr Sayoc for the past several years living in the white van with distinctive stickers.

“I knew right away it was him when I saw the pictures of the van today in the news,” Mr Prado said Friday afternoon.

“That van was his home. It was really smelly when he had the door open and you walked by. It was horrible. He might drive off and run an errand or something, but every morning that van was there in the parking lot.”

-The New York Times