The beneficiaries of the South Texas Syndicate Trust were ripped off by its one-time trustee, JPMorgan Chase Bank, in its management of valuable mineral rights in the heart of the Eagle Ford Shale, a lawyer for the beneficiaries told jurors during the opening of a trial Wednesday.

More than half of the trust's approximately 280 beneficiaries sued the nation's largest bank in 2010 in Bexar County District Court alleging the bank put its interests ahead of the rights holders. The trust owns the mineral rights to 132,000 acres in LaSalle and McMullen counties. It's the site of the Eagle Ford's first discovery well.

"The bank entered sweetheart deals with its commercial clients for our mineral rights, and the bank tried to cover it up," Jim Flegle, the lawyer for the beneficiaries, said in his opening statement.

Lawyer Charles "Chuck" Gall, representing JPMorgan, countered that the bank had hard-working people who did a "really good job" of managing the trust for the beneficiaries, who made "hundreds of millions of dollars" from mineral-rights leases.

The trial's opening was put on hold Friday after both sides told Judge Larry Noll they were trying to finalize a settlement. The parties have an "agreement in principle," but were not able to document it, Gall said. Wednesday, Noll gave the lawyers a choice of going forward with the trial or having the case dismissed altogether.

Dan Sciano, one of the lawyers for the beneficiaries, said outside of court that settlement negotiations were expected to continue during the trial. Two or three matters must be resolved, he said.

The beneficiaries allege JPMorgan entered into leases at rates and terms that were bad for them but lucrative for the bank's commercial clients. The beneficiaries say in the suit that they received about $32.5 million in payments from leases JPMorgan executed with its commercial clients, including Petrohawk Energy Corp. and Broad Oak Energy. But the suit says the bank's commercial clients benefited by more than $1.1 billion.

JPMorgan participated in a more than $1 billion line of credit for Petrohawk in 2008, the same year it the bank leased some of the trust's mineral rights to the company, Flegle said to jurors.

The beneficiaries are suing for more than $415 million, not including attorney fees. The figure includes $322 million in lost bonus damages. Bonus payments are made on the front end of a mineral lease.

A court document JPMorgan filed in a related case calculated the trust distributed about $210 million from 1998 through April of this year, shortly before the bank was replaced as trustee by the Bank of Texas.

"We negotiated prudent leases that have generated millions and millions of dollars to them, and will continue to generate millions and millions of dollars to them," Gall said.

The beneficiaries are using the benefit of "hindsight" to "second-guess" decisions made by JPMorgan, Gall added. "A trustee's duties and responsibilities are not to be judged by hindsight. It's just another way of saying, no Monday morning quarterbacking."

Flegle said the plaintiffs were not acting on hindsight, but on "what was known, or could have been known, at the time decisions were made." He cited known oil and gas plays prior to 2008, including the Barnett Shale, the Bakken Shale and Marcellus Shale, as examples.

The beneficiaries take issue with various lease terms JPMorgan executed, including the nearly 80,000 acres leased to Petrohawk. They maintain that if JPMorgan had waited and assessed what was happening in the Eagle Ford, it could have obtained bonuses of $1,200 per acre after October 2009 and $10,000 per acre after May 2010 instead of the $200 an acre they received.

The trial is expected to take four to six weeks.