Martin Shkreli exits federal court Thursday in Brooklyn. (Jeenah Moon/Bloomberg News)

NEW YORK — Sarah Hassan was new to the hedge-fund world in 2010 when a longtime friend of her father suggested she meet a “rising star” in the industry: Martin Shkreli.

The friend, Brent Saunders, the chief executive of pharmaceutical giant Allergan, said he’d had “some phenomenal returns” by investing in one of Shkreli’s funds, Hassan told a federal jury in Brooklyn this week. “Mr. Saunders had suggested we meet up because I was trying to learn about the hedge-fund world,” she said. “He thought Martin could be mentor.”

Hassan eventually met Shkreli for lunch at a Manhattan restaurant, during which he recommended some books to read and gave general advice about wading into hedge-fund investing. Hassan would go on to invest $300,000 in one of Shkreli’s hedge funds, MSMB Capital.

So marked the start of a business relationship that produced a handsome windfall but would eventually lead to Hassan testifying this week against Shkreli as he stands trial for allegedly defrauding investors and committing securities fraud. Hassan’s dealings with Shkreli offered a window into the workings of the lucrative hedge-fund world and illustrated the tension at the heart of the prosecution’s case: The victims ultimately made money.

In the year after Hassan’s initial investment, prosecutors say, MSMB Capital would take massive losses that Shkreli failed to tell Hassan and other investors about. Instead, they allege, Shkreli launched into a multi-year scheme to loot other enterprises he founded to repay investors and hide his failed stock bets.

And yet Shkreli’s attorneys say Hassan walked away with more than $1 million after her initial $300,000 investment.

Whether Shkreli’s investors were actually defrauded emerged as a central theme during the early days of a trial that could run six weeks or so. His case has drawn national media attention as much for the charges he faces — he could be sentenced to more than 20 years in prison — as for his history as the head of a pharmaceutical company that sharply raised the price of  a 62-year-old drug primarily used to treat newborns and HIV patients. Fueling that notoriety has been a boisterous personality and social-media habit that has flustered even his attorneys at times.

Shkreli, a wiry child of immigrants from Albania and Croatia, can often appear awkward in public, an image that his defense attorney, Benjamin Brafman, did not shy from during his opening statements. “Is he strange? Yes. Will you find him weird? Yes,” Brafman said earlier this week.

[‘He was born this way’: Martin Shkreli’s attorney offers defense as securities-fraud trial opens]

But for all his outrageousness, another image, of a well-connected Wall Street insider, emerged during testimony this week.

Josiah Austin, a Texas ranch owner and member of the board of directors of a biosciences firm who manages $300 million of his own money through a firm called El Coronado, said he met Shkreli in 2005 or 2006 at a bank conference and was immediately impressed.

“I thought Martin was young, smart and a little cocky. You know, I liked Martin,” he said. “He wanted to make a lot of money. Martin Shkreli wanted to be Stevie Cohen.” Cohen is a billionaire hedge-fund manager.

Austin said he sometimes spoke with Shkreli on a weekly basis and even agreed to pay several months’ rent to help Shkreli’s sister, whom he didn’t know personally. Even after losing nearly $5 million in one of Shkreli’s early hedge funds, Austin said, “I still thought Martin was an intelligent, smart guy, but I didn’t particularly want to do any more business with him.”

Like Austin, Hassan also had ties to the drug industry. Hassan is the daughter of Fred Hassan, a partner at Warburg Pincus, former chairman of Bausch & Lomb and former chairman and chief executive of Schering-Plough.

At their first meeting, Shkreli said his hedge fund had $40 million to $50 million in assets, Sarah Hassan said. (Prosecutors say it was much less.) “He seemed to be pretty smart,” she said. He “talked fast, was sometimes a little distracted.” Hassan said she wanted to build a business relationship with Shkreli, noting that her $300,000 investment represented about 30 percent of her $1 million in personal net worth.

About a month after Hassan invested,  Shkreli emailed her to say that her investment had increased to $324,600. “I was fairly ecstatic,” she said. “I was quite excited about the investment.”

[‘Pharma Bro’ Martin Shkreli trial hits speed bump: Finding jurors who don’t already dislike him]

Shkreli’s relationship with Hassan helped him snag a rare meeting with her pharmaceutical-industry-giant father. Fred Hassan testified Friday that he met with Shkreli for 20 to 30 minutes as a “favor” to his daughter at an industry conference. “He was a pleasant person, a little intimidated by me,” Fred Hassan testified. “He had done his homework on me.” (His daughter would later complain that Shkreli was conflating her investment in Shkreli’s hedge fund with her father, who was not involved.)

Later, Shkreli approached Sarah Hassan about investing in Retrophin, a pharmaceutical company he had started. The company would focus on “orphan” drugs that treat rare conditions. “You can make a lot of money on orphan drugs, because the price per patient is quite high,” she said he told him. After being told other wealthy people were also backing the company, Hassan invested $150,000 from her family’s personal hedge fund, DynaGrow.

Eventually, Hassan testified, Shkreli notified her that he was shutting down his hedge fund but became evasive when it came to returning her money. He later told her that it had all been put into Retrophin, which Hassan testified she did not realize could happen. “I felt somewhat betrayed at this point,” said Hassan, 27. “It just wasn’t right.” Prosecutors say that Shkreli stole from Retrophin shareholders to pay off his debts to his hedge-fund investors.

Under cross-examination, Brafman repeatedly returned to the profit Hassan eventually made from the transaction. In addition to $400,000 in cash, she was given more than 50,000 shares in Retrophin, which she later sold for about $900,000. Shkreli “more than tripled your money,” he said. “At the end of the day you made a hefty profit?”

Yes, Hassan said, “even more than I asked for.”