BANGOR, Maine — Jurors began deliberating Friday to determine whether attorneys at a local law firm were negligent in negotiating the sale of three Hancock County campgrounds, or whether the former owner understood the terms of the deal from the start.

A trial in the lawsuit Patty Rae Stanley of Memphis, Tenn., filed against Bangor attorneys Daniel G. McKay and Sarah S. Zmistowski and Eaton Peabody, the law firm for which they work, began June 6 in U.S. District Court.

The former owner of Mount Desert Narrows Campground in Bar Harbor, Mount Desert Narrows Too Campground in Trenton, and Patten Pond Campgrounds in Ellsworth sued her former attorneys and the law firm in August 2010. The lawsuit was filed in federal court because Stanley lives out of state and is seeking more than $75,000 in damages.

Stanley claims her properties were worth at least $14.5 million, more than twice what she received for them. Her former attorneys have said in court documents that the campgrounds were worth the $6.75 million Stanley was paid for them.

The 70-year-old widow is seeking a total of $7.75 million in damages — a total arrived at by subtracting the $6.75 million she was paid from the value Stanley placed on the property, her attorney, Michael Waxman of Portland, told the jury in closing arguments Friday.

Stanley has claimed that her lawyers did not follow professional standards in drawing up her sale agreement with Equity Lifestyle Properties Inc. of Chicago or protect her interests.

“This case is about three things — trust, betrayal of trust and a major misunderstanding,” Waxman said in his closing argument. “ELS, a guerilla in the market, came in and stripped her of more than half the value of her campgrounds and the attorneys she hired and trusted failed to explain the deal to her. If they had just spent the time necessary to explain the deal to her, we wouldn’t be here.”

The attorneys claim they and the firm properly represented Stanley and that she understood the provisions of the sale.

Portland attorney Peter Rubin in his closing argument pointed to 11 documents and emails that had been introduced as evidence that prove Stanley understood and approved the deal. He told jurors that Stanley knew she would stay on to manage the campgrounds, but would get no money several years down the road unless business was better than it had been the summer of 2004. Business did not improve in the summers of 2005, 2006 or 2007 due to bad weather and rising gas prices.

“She needs to accept her own personal responsibility here,” Rubin said. “She took a business risk and it didn’t work out. The evidence clearly shows that Ms. Stanley knew from the beginning the terms of the deal.”