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The grandmother of Medal of Honor recipient Dakota Meyer, who has filed suit against a former employer over claims that he is mentally unstable and a problem drinker, came to the defense of her hero grandson on Wednesday, telling FoxNews.com that, "I've never, ever known him to be a drinker."

Meyer, a 23-year-old Marine Corps sergeant who received the nation's highest honor from President Obama in a White House ceremony in September -- two years after his heroism was credited for saving 36 lives during a six-hour ambush in Afghanistan -- filed legal papers in Texas on Monday.

His lawsuit claims that defense contractor BAE Systems retaliated against him for objecting to the company's sale of high-tech sniper scopes to the Pakistani military. Meyer claims a manager at the British company said he was "mentally unstable" and had a "problem related to drinking in a social setting," according to the lawsuit.

Jean Meyer, the Marine's 81-year-old grandmother, told FoxNews.com those allegations were unfounded.

"I've known him for all of his life and I've never, ever known him to be a drinker," she said. "That's all I can tell you."

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Meyer, of Green County, Kentucky, said she helped raise the veteran along with his father, Michael.

"That boy has never done anything that we had to get on him about or punish him for -- nothing," she said. "You couldn't have asked for a better boy growing up and he still is. He would do anything in the world for anybody."

Meyer said she last saw her grandson two or three days ago. He is currently traveling to New York, according to his father, who declined additional comment when reached Wednesday.

"We were all down for Thanksgiving," Jean Meyer said. "We just had a good time."

Asked about her grandson's mindset, Meyer replied: "Dakota is always in good spirits. He has not said anything [about the lawsuit] and we have not asked him."

Regarding allegations that her grandson is a problem drinker, Meyer replied: "That's not true, and I've been around him all his life."

The lawsuit, which was first reported by The Wall Street Journal on Tuesday, seeks unspecified damages.

In a statement to FoxNews.com on Wednesday, BAE Systems spokesman Brian Roehrkasse said the company was "incredibly grateful" for Meyer's service and bravery.

Meyer was employed as a construction worker in Kentucky when he was awarded the Medal of Honor. In September 2009, a then-21-year-old Meyer defied orders by charging five times in a Humvee into heavy gunfire and provided cover for his team, allowing many to escape likely death. He killed at least eight Taliban insurgents.

"Although we disagree with his claims, which we intend to defend through the appropriate legal process, we wish him success and good fortune in all his endeavors," the statement read.

Roehrkasse said the State Department -- not BAE -- makes the decision on which defense-related products can be exported, including those to Pakistan.

"In recent years, the U.S. Government has approved the export of defense-related goods from numerous defense companies to Pakistan as part of the United States’ bilateral relationship with that country," the statement continued.

The technology Meyer apparently protested was, according to the State Department, a type of thermal-imaging rifle scope.

State Department spokesman Mark Toner said Tuesday that the U.S. government in August approved a "marketing license" allowing the company to "temporarily export" up to 20 of the scopes to Pakistan. But he said the approved export of the scopes did not count as a sale, since they were for demonstration purposes only.

According to the lawsuit, BAE hired Meyer in March, but the relationship quickly soured. Meyer said he became dismayed in April upon learning that BAE had pursued sales of weapons systems to Pakistan, later sending an email to his supervisor expressing his disapproval.

Meyer wrote that it was "disturbing" how U.S. troops were being issued outdated equipment when better, advanced thermal optic scopes were being offered to Pakistan.

"We are simply taking the best gear, the best technology on the market to date and giving to guys that are known to stab us in the back," Meyer wrote in the email, according to the lawsuit.

Meyer claims his supervisor began berating and belittling him after sending the email, at one point allegedly taunting him about his Medal of Honor by calling it Meyer's "pending star status." That supervisor, Bobby McCreight, is also named in the lawsuit and is still employed by BAE. Roehrkasse said McCreight is a former decorated Marine sniper.

McCreight is unavailable for comment on the lawsuit, Roehrkasse said.

Meyer resigned from BAE in May. He then tried obtaining a job at a former employer, San Diego-based Ausgar Technologies, but the lawsuit claims the opportunity fell through after McCreight characterized Meyer as a poor employee during a conversation with a manager who had to approve new hires.

"Bottom line, it was determined that ... you were not recommended to be placed back on the team due to being mentally unstable and no performing on OASYS tasks assigned," according to an email from an Ausgar manager included in the lawsuit.

Valerie Ellis, an administrator at Ausgar, said the company had no comment when reached Tuesday. Attorneys for Meyer did not return a phone messages seeking comment.

Pentagon and Marine officials also declined to comment on the lawsuit when reached on Wednesday.

"It is between Dakota Meyer and BAE," one source said.

In a statement to FoxNews.com, the Marine Corps Scholarship Foundation said it honors Meyer for his "undisputed heroism" and his commitment to assist wounded Marine families through his relationship with the foundation. Meyer is in the process of raising $1 million for the organization, spokeswoman Eugenia Gardner said. It was not immediately clear how much Meyer had raised thus far, she said.

Fox News' Jennifer Griffin and The Associated Press contributed to this report.