EULESS, Texas -- The parents of a Texas A&M football player are upset that a Brazos County justice of the peace ruled the cause of death as natural instead of accidental.

Eighteen-year-old Brandon Fails of Euless died on Nov. 25 after collapsing in his Texas A&M dorm room. The Travis County Medical Examiner's Office said he died of a blood clot in his lung and said the cause of death was accidental.

Brazos County Justice of the Peace Margaret Meece signed the death certificate on Thursday and cited death from natural causes.

"They're saying that Brandon died of natural causes. We're wanting to know what is making them state that he died of natural causes when we know that he had an operation and everything and he passed away,'' Fails' mother, Valerie, told The Associated Press Tuesday night.

"So what's making them decide that Brandon died of natural causes when they're going against what the coroner said?'' she said.

It is unclear where the clot originated. Fails, who was 6-foot-4 and 275 pounds, had undergone arthroscopic surgery on his right knee weeks before his death.

How the clot formed could be important for Fails' family. Texas A&M sports information director Alan Cannon said that the school has a $100,000 "practice and play death benefit'' available for families of students who die as a result of sanctioned athletic activity.

A clot resulting from surgery stemming from a football injury likely would qualify for such a benefit. Cannon said the benefit is determined by the university's insurance and risk management department.

Meece concluded in her report that she can't specify which leg in which the clot formed, nor can she conclude that the cause of death was "accidental,'' from a clot that formed as a result of the injury or surgery.

"How in the world did she come up with that conclusion? Surely there must be some substantive information she relied upon to come up with that conclusion,'' Charles Fails said in an interview with Dallas-Fort Worth television station KDFW.

Meece told the AP in an interview Tuesday that the knee injury was six weeks prior to Fails' death, and the surgery was five weeks prior to his death.

The clot was large, and her research concluded that it couldn't have been more than 10 days old, so it couldn't have formed as a result of the injury or the surgery.

"This was a massive clot. They think it formed no more than 12 hours before he died,' she said, referring to Bryan doctors she had questioned. "There is no way that clot could have been around long enough to have been caused by the injury or the surgery.''

Charles and Valerie Fails have retained attorney Royce West of Dallas. West is also a state senator.

As of Tuesday, the Fails had not received a death certificate, although they were told by West that it had been signed last week.

"I want justice for my son now that he's passed away,'' Valerie Fails said. "He's not here to fight his battle, so being parents, that's what we want. They are justices of the peace for law and order, and we want justice.''