Martin Shkreli, the pharmaceutical CEO who soon became reviled for his decision to ramp up the price of AIDS medication from $13.50 to $750 per pill, was arrested by the FBI Thursday on federal securities fraud charges.

The charges don't relate to Turing Pharmaceuticals, the company that he is currently CEO of, but rather his time as CEO of Retrophin, a firm that he founded in 2011, according to Bloomberg.

He was dumped from that company in September 2014 following allegations that he illegally took stock from the firm in order to pay off debts from unrelated business dealings. The company has since filed a lawsuit against him, accusing him of using the firm as his personal bank to help pay off investors who lost money at his old hedge fund, MSMB Capital Management, taking $65 million from Retrophin in the process.

"Shkreli was the paradigm faithless servant," Retrophin's complaint stated, according to The New York Times. "Starting sometime in early 2012, and continuing until he left the company, Shkreli used his control over Retrophin to enrich himself and to pay off claims of MSMB investors (who he had defrauded)."

Shkreli recently purchased a majority of the shares and became CEO of KaloBios, another publicly-traded drug company, reported CW's California affiliate KTLA 5. News of the takeover caused shares to soar 400 percent, with shares since doubling in value. However, they have since plunged 50 percent in premarket trading Thursday following news of his arrest.

In the meantime, Shkreli is unfazed. "The $65 million Retrophin wants from me would not dent me," he said in regards to Retrophin's lawsuit. "I feel great. I'm licking my chops over the suits I'm going to file against them."