As the FBI stood poised to arrest him, he allegedly live-streamed a phone call from an investigator, then hung up on him.
His securities fraud scheme was labelled a "trifecta of lies, deceit and greed", and when the charges stuck, a US court struggled to arrange a fair trial because he was so unpopular with jurors.
But he's rich and unrepentant. And it seems he has no plans to change that soon.
Last week, Shkreli was found guilty of two counts of securities fraud and a count of conspiracy after a trial with a Shkreli-led sideshow described as a circus.
The charges had nothing to do with his pharmaceutical drug price-gouging. He was, prosecutors said, essentially running a Ponzi scheme in which he looted a drug company he founded, Retrophin, of $11 million in stock and cash to pay back investors in two failed hedge funds he ran.
Prosecutors said he lied to his hedge-fund clients about their steep losses, and that he used Ponzi-style tactics to rob one bank to repay another.
In court, investors accused him of keeping them in the dark as his scheme unravelled.
He argued - still does - that there was not harm done, because all of them got rich off Retrophin stock.
And in the wake of the guilty verdict, he says the fact he was acquitted of five other charges is a win.
"In sum and substance I feel exonerated," he said, adding he thinks there's a "50-50 chance" he won't face any punishment.
'Jail doesn't scare me'
He's still awaiting sentencing, and could be imprisoned for up to two decades, but that hasn't silenced him in the slightest.
In the wake of the guilty verdict, he said jail didn't frighten him - because he saw 9/11 and won't be going to a hard-core prison anyway: "no shanks".
He Facebook live-streamed his lack of remorse to the world.
Holding his cat in his lap, he trash-talked his critics, hurled obscenities and predicted that his acquittal on some charges would help him recover tens of millions of dollars he claims he's owed from a drug company he started.
"It doesn't seem like life will change much for Martin Shkreli," he said, drinking a beer and live-streaming on YouTube an interview with a journalist about the verdict and the possibility of jail.
"I'm one of the richest New Yorkers there is, and after today's outcome, it's going to stay that way.
"I grew up on the mean streets of Brooklyn. I was across the street from 9/11; I've built businesses from zero to hero, many times over. A few months in jail does not scare me."
He seemed not to care that judges may take a dim view of his lack of contrition when it comes time for sentencing. And he believes he won't go to jail anyway - or at most spend only up to two years in a prison cell.
Unapologetic
Shkreli's own lawyer admits his client has an image problem.
"Martin is a brilliant young man, but sometimes people skills don't translate well," said Ben Brafman after the guilty verdict.
"There is an image issue that Martin and I are going to be discussing in the next several days."
Shkreli's live stream indicated he had no plans to change his ways.
"Ben probably wants me to act and look like your average CEO, but I'm a very individualistic person and I don't sort of conform to what folks want me to do and not want me to do, and that's what being an individual is all about," he said.
'Pharma Bro' booted off Twitter
The 34-year-old is as notorious for his snide "Pharma Bro" persona on social media, as he is for price-gouging, and had his wings clipped when he was banned from Twitter in May.
The permanent ban came after he was temporarily booted in January after allegedly harassing several female journalists, including Lauren Duca, a Teen Vogue contributing editor who wrote a critical op-ed of then-President-elect Donald Trump.
After he asked Duca to attend Trump's inauguration the following week - prompting her to tweet, "I would rather eat my own organs" - Shkreli boasted about buying the domain name "MarryMeLauren.com," which flooded the web with Photoshopped snaps of Shkreli with Duca.
Shkreli also made his Twitter page into a creepy, stalkerish tribute to Duca. She tweeted an image of it to Twitter CEO Jack Dorsey, asking: "How is this allowed @Jack."
He lost his Twitter account, but he hasn't eased up on trolling Duca.
Ahead of last week's verdict, he was at it again.
"Trial's over tomorrow, b****s. Then if I'm acquitted, I get to f**k Lauren Duca," he said, on the eve of the jury going out to consider its verdict.
Circus continues
The self-taught biochemist refuses to concede remorse, telling a journalist "my investors should have remorse for me".
During the trial, Brafman said his client was "annoying", but his hedge fund investors knew what they were getting.
"They found him strange. They found him weird. And they gave him money. Why? Because they recognised genius," he said.
Shkreli didn't testify in court, but a picture of the "quirky defendant" painted in evidence included how he slept on the floor of his office in a sleeping bag for two years; how a drug company board member and former American Express executive wrote an email he'd meet with Shkreli "only if I can touch your soft skin"; how Shkreli wrote a letter to the wife of an employee threatening to make the family homeless if the man didn't settle a debt.
He didn't appear on the stand, but Shkreli used Facebook to criticise prosecutors and news organisations and complain the case was a "a witch hunt of epic proportions".
He kept up the commentary even after the judge ordered him to keep his mouth shut in and around the courtroom after another rant to new reporters covering the trial.
Shkreli believes he'll spend anywhere from no time to 24 months in a cell.
Meanwhile, he's on $5 million bail, awaiting sentence, and his lawyers are planning to appeal.
"Mr Shkreli, I wish you well," the judge said after the guilty verdict was read. "I'll see you soon."
Most likely on Facebook.
