When directors of Mariner Energy met by telephone on April 7, 2010, board member H. Clayton Peterson was given sensitive and confidential information: another oil and gas company was offering to buy Mariner.

Instead of keeping the information under his hat, Peterson called his son Drew Clayton Peterson the next day and told him to buy Mariner shares, the government says.

And later that day, during a visit to the gym, the younger Peterson told a close friend who ran a hedge fund that he, too, should consider buying Mariner stock.

When the merger with Apache was finally announced, the hedge fund reaped illegal trading profits of about $5 million, the government says.

Drew Peterson and others close to him netted about $150,000, the government said.

But the profits were illusory.

The two Petersons pleaded guilty Friday to federal insider trading charges. They face potential prison sentences and agreed to give up their illegal trading gains.

The hedge fund chief executive, described in court filings as a “co-conspirator,” was not named. But that doesn’t mean he’s off the hook. As part of a plea agreement, Drew Peterson agreed to tell law enforcement officials everything he knows and, if asked, testify before a grand jury.

The case against the Petersons was the latest in a string of insider-trading prosecutions suggesting that many people, when they gain access to confidential market-moving information, have little hesitation about cashing in.

In the past week alone, the Securities and Exchange Commission settled civil insider trading charges against former Baltimore Orioles third baseman Doug DeCinces and former Illinois legislator William Marovitz, son-in-law of Playboy founder Hugh Hefner.

The Peterson case contains echoes of the SEC’s complaint against former Goldman Sachs director Rajat Gupta, who was accused of leaking boardroom secrets to hedge fund billionaire Raj Rajaratnam. The SEC this week withdrew its administrative complaint against Gupta but reserved the right to sue Gupta in federal court. Gupta, who denied the allegations, challenged the SEC over procedural issues.

Clayton Peterson, 65, was chairman of the Mariner board’s audit committee, which means he was supposed to serve as a watchdog over the Houston-based energy company. He was a managing director of Arthur Anderson and spent 33 years at the accounting firm, which imploded after its audits of Enron and WorldCom were called into question.

Now retired, he resides in Denver, Phoenix, and Cabo San Lucas, Mexico, the SEC said in a civil complaint.

He resigned this week as a board member of RE/MAX, the realty company.

“This came as a complete shock to us,” RE/MAX spokesman Shaun White said. “He had a stellar reputation for just being one of the most trustworthy people.”

Clayton Peterson’s attorney, Steven Glaser, said in a statement: “Clayton Peterson has accepted responsibility for his conduct in this matter, which was an aberration from his otherwise long and distinguished career.”

An attorney for Drew Peterson did not respond to a request for comment. Drew Peterson, 35, lives in Denver and has worked as a licensed financial adviser.

According to a Justice Department court filing, Clayton Peterson called his son on April 8, 2010, and, noting that he “had participated recently in a number of Mariner board meetings,” told his son to buy Mariner shares for a family member.

Later that day, when Drew Peterson told his friend the hedge fund chief executive that it appeared “that a significant event was about to happen involving Mariner,” the two speculated about who might be buying the company, the government said.

The father allegedly updated the son about the merger talks, and the son allegedly updated the hedge fund manager, at one point leaving “a short, coded voice mail message” confirming that Mariner was being acquired, the government said.

In time, the son bought stock for a sister, a niece, four clients, a friend and an investment club called “Blind Seven.” The hedge fund manager invested in options for himself, his fund and family members, the government said.

One of the calls between father and son took place while the son was driving with another friend to a Denver Nuggets basketball game, the government said. After hanging up, the son advised the friend to buy Mariner stock, too.