The jury voted to convict on counts in which they saw fraudulent intent to take money, the juror said.

At Mr. Shkreli’s trial, prosecutors, defense lawyers and witnesses provided sharply different takes on the defendant as they described how he rose from an ambitious young hedge fund manager to a notorious pharmaceutical executive.

The prosecution brought forth an “avalanche” of evidence, as the prosecutor Jacquelyn Kasulis put it in her rebuttal argument, that Mr. Shkreli illegally used Retrophin to repay the defrauded MSMB investors. The evidence included a threatening letter he sent to the wife of a former employee; statements he sent to MSMB investors showing great returns at the same time he had no money in fund accounts; three versions of a backdated agreement to make it look as if MSMB Capital had invested in Retrophin when it had not; and claims about assets under management that were wildly out of line with his actual fund size.

“It’s time for Martin Shkreli to be held accountable,” she said.

His lawyers focused on the fact that his investors ultimately made back much more than their initial investments. They said that was proof that Mr. Shkreli had never intended to commit fraud. Instead, they said, he worked hard to get Retrophin off the ground so he could reimburse MSMB investors.

“He did it, and it worked, and they got paid,” Mr. Brafman said in his closing statement. “When they got the financing, they started to pay these people, not to loot Retrophin.”

However, prosecutors said that paying Mr. Shkreli’s old investors was not the responsibility of Retrophin, a public company, and that Mr. Shkreli had misled his MSMB investors. “Lying to people to get them to invest with you is fraud,” Ms. Kasulis said in her final statement.

Mr. Shkreli is the child of Albanian immigrants. He was raised in Brooklyn and attended Hunter College High School, one of the city’s elite public schools. He went to Baruch, one of New York’s city colleges, and landed an internship at Cramer Berkowitz, going on to other money-management jobs.