NEW YORK — Federal authorities revealed charges Tuesday against three hedge fund portfolio managers and a hedge fund analyst, describing a paper-shredding, flash drive-destroying panic that ensued when they thought they faced the scrutiny of investigators.

The two new arrests and the announcement of two guilty pleas expanded a federal crackdown on insider trading that masks itself as legitimate market research.

The case raised the number charged in the probe to 12. The Securities and Exchange Commission said the conspiracy earned more than $30 million in illegal profits.

“Shred as much as u can,” one of the men wrote to another in a string of electronic messages that were traded after they saw news reports describing U.S. Attorney Preet Bharara’s assault on Wall Street insider trading, according to a criminal complaint filed in U.S. District Court in Manhattan.

One of the four told investigators he even destroyed computer drives and scattered the pieces in several garbage trucks.

Bharara on Tuesday promised more arrests, saying “we are far from finished.”

The investigation was revealed in the fall and has so far concentrated on a group of hedge fund portfolio managers who authorities say tried to learn inside information about public companies through contacts at a California-based public research firm, Primary Global Research.

The company boasted of its research results, but authorities say it sometimes specialized in linking corrupt employees of public companies willing to prematurely divulge earnings results or acquisition announcements with hedge fund managers eager for a trading edge.

In court papers, charges were outlined against Samir Barai, 38, who owned a New York-based hedge fund company that bears his name; Donald Longueuil, 34; Noah Freeman, 34; and Jason Pflaum, 37. Freeman and Longueuil were described as hedge fund portfolio managers while Pflaum was described as a research analyst.