Phil Mickelson's harshest jury might be PGA Tour commissioner Tim Finchem

If I'm Tim Finchem, Commissioner of the PGA Tour, the least of my worries is that Phil Mickelson is being shadowed by some FBI agents at an event in what appears to be an attempt to pressure him in a Wall Street insider-trading investigation.

No, if I'm in Finchem's chair, I'm a whole lot more concerned that because of the investigation, an association between one of my sport's bigger stars and a well-known sports gambler is out in the open.

Billy Walters is a Las Vegas developer and businessman who also happens to be perhaps the most successful sports gambler in the country. He was among the first to utilize computer models to aid his wagering.

He also owns some golf courses in the Las Vegas area and has been profiled on Golf Channel and by the CBS news magazine "60 Minutes."

Mickelson, a former Arizona State standout, reportedly has played golf with him on several occasions, including in a pro-am event.

And when Walters plays golf, there usually is something more than bragging rights on the line. In that 2011 "60 Minutes" interview, Walters said he has played a round of golf with as much as $1 million on the line and once won $400,000 by holing a long putt.

He also said in that interview that there are "many more" thieves wearing suits and ties on Wall Street than among Las Vegas sports bettors.

And he's probably right.

The other player in the investigation reportedly is the activist investor — some would call him a "corporate raider" — Carl Icahn, who has denied knowing Mickelson or being aware of an investigation by the Securities and Exchange Commission or FBI.

The investigative theory apparently is that Icahn told Walters, or someone Walters knows, that he planned to make a hostile bid to take over Clorox. Walters, Mickelson and others had purchased call options in Clorox.

A call option gives the investor the right to purchase a stock at a given price within a given time frame. But the investor is not obligated to buy.

When Icahn announced publicly his bid, the price of Clorox stock spiked, and the investors made big bank by exercising the options.

The Wall Street Journal reported that a couple of FBI agents followed Mickelson during his opening round at the Memorial last week, then approached him to ask questions after his round. He referred them to his attorneys.

Mickelson confirmed that the Journal description of the FBI encounter was accurate. He reportedly would not comment on a New York Times report that he had been questioned about a year ago when he got off his private plane at Teterboro Airport in New Jersey.

He insisted he has done "absolutely" nothing wrong and that he is cooperating with the investigation.

It's all juicy stuff, especially considering that the U.S. Open unfolds next week at Pinehurst Resort and Golf Club's No. 2 course, and Mickelson was runner-up in the Open last year, a record sixth second-place finish at the national championship.

Mickelson, now 43 years old, has won five major championships. He needs to win a U.S. Open to become only the sixth player to win golf's career Grand Slam of the Open, British Open, Masters and PGA Championship (seven if you include Bobby Jones, who won the pre-Masters tournament version of the U.S. Open, U.S. Amateur, British Open and British Amateur).

Pardon the expression, but it's a safe bet golf fans at Pinehurst still will be pulling for Lefty.

An insider-trading investigation isn't likely to hurt Mickelson's popularity one bit. Let's face it. We all know the rich and connected operate in different circles than the rest of us, and profit from it.

Just last year, Scott London, a senior partner at the accounting giant KPMG, pleaded guilty to providing insider tips on the stocks of Herbalife and Skechers USA to one of his golf partners. KPMG had served as outside auditor for those two companies.

If KPMG sounds familiar, maybe that's because Mickelson endorses the company and wears those initials on his golf cap.

Coincidentally, Herbalife is among the companies in which Icahn has taken a substantial or controlling interest in the past.

At any rate, fans are likely to give Mickelson a pass for hanging out with Walters and making a few wagers on sports through the years. It is well-documented that Mickelson has won some big bets.

But Finchem might not be as generous.

Associating with gamblers always has been taboo in sports. True, one golfer in a field that usually goes up to 144 players in a PGA Tour event isn't likely to be of much use to a gambler.

But what about events such as the Ryder Cup or the President's Cup, which generate substantial action on the outcome of the event and on individual matches and the records of individual players?

Those would be fairly easy to manipulate.

This isn't to suggest Mickelson is doing something like that, or that he has done anything wrong in terms of his investments, either.

But even if nobody is trying to take advantage of the gambler-athlete relationship, it always brings the integrity of the game into question.

And that's something Finchem has to protect.

Reach Young at 602-444-8271 or bob.young@arizonarepublic.com. Follow him on Twitter @BobYoungTHI.