BOSTON >> Lawyers for former NFL star Aaron Hernandez formally asked a court today to dismiss his first-degree murder conviction now that he has died.

Under a long-standing Massachusetts legal principle, courts customarily vacate the convictions of defendants who die before their appeals are heard.

Legal experts say the doctrine holds that it is unfair to defendants or their survivors if a conviction is allowed to stand before they had an opportunity to clear their names on appeal in case some kind of error or other injustice was determined to have occurred at trial.

Hernandez hanged himself at a maximum-security state prison last week, just days after he was acquitted of fatally shooting two Boston men in 2012. He was serving life without parole in the 2013 murder of Odin Lloyd, a semi-pro football player,

Linda Thompson, one of Hernandez’s appellate attorneys, said the conviction in the Lloyd case is not considered final because the automatic appeal he was entitled to had not yet been heard at the time of Hernandez’s death.

“Since the conviction is not final because the appeal has not been decided, there’s nothing that can be done with the appeal,” Thompson said. “There is not going to be a conviction because it can’t be pursued in the court system.”

The Bristol district attorney’s office, which prosecuted the Lloyd case, will oppose the motion to vacate Hernandez’s conviction, said spokesman Gregg Miliote. He did not immediately say on what grounds the district attorney would challenge the dismissal.

Doug Sheff, an attorney who represents Lloyd’s mother, Ursula Ward, in a wrongful-death lawsuit against Hernandez, said he doesn’t believe the civil case will be undermined if the conviction is vacated.

“We believe that a well-reasoned court will protect the rights of innocent, grieving family members like Ursula Ward and allow us to proceed with our wrongful-death case directly,” Sheff said.

Hernandez’s funeral was held Monday.

Vacating a conviction after the death of a high-profile defendant has precedent in Massachusetts.

The child molestation conviction of former Roman Catholic priest John Geoghan, a key figure in the clergy sex abuse scandal that rocked the Boston archdiocese, was dismissed after he was beaten to death in prison in 2003.

John Salvi, convicted of killing two abortion clinic workers and wounding five other people in 1994, also had his convictions tossed after he killed himself in prison.