FALL RIVER — A key figure in the murder case against former New England Patriots player Aaron Hernandez pleaded not guilty Thursday to a charge of being an accessory after the fact of a slaying, which authorities say was orchestrated by the star athlete.

Ernest Wallace, 41, replied, “Not guilty, your honor,” in a quiet but firm voice when asked how he pleaded to the charge during a brief arraignment in Bristol Superior Court.

He was ordered held on $500,000 cash bail pending a hearing Sept. 26, when his lawyers may seek a bail reduction.

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His lead attorney, David Meier, said in court that he wanted to view the minutes of grand jury proceedings that led to Wallace’s indictment.

The minutes were later turned over to the defense, District Attorney C. Samuel Sutter said outside court.

Neither Meier nor prosecutors discussed specifics of the allegations against Wallace, but Sutter suggested that more evidence will be presented at the next hearing. He said prosecutors will have to be “very forthcoming” about evidence to ensure bail remains at $500,000.

“I think it is a very safe assumption that during the bail hearing you will learn about matters that you’re not aware of right now,” Sutter said. “This is a very serious offense. Accessory after the fact of murder [carries] a seven-year state prison sentence. We allege that he assisted, in a material way, Aaron Hernandez after the fact of the murder of Odin Lloyd.”

Meier left the court without commenting.

Hernandez, 23, is facing murder and weapons charges in the June 17 slaying of Lloyd, 27, of Dorchester. Lloyd was found dead with multiple gunshot wounds near Hernandez’s North Attleborough home.

Hernandez has pleaded not guilty to all charges and is being held without bail. His lawyers have said that the case against him is weak and that they believe he will be cleared.

A third man, Carlos Ortiz, 27, is facing a weapons charge in connection with the case.

According to prosecutors, Wallace and Ortiz were in a vehicle with Hernandez when he picked up Lloyd in Boston on the night of the killing. Prosecutors say that Hernandez, Wallace, and Ortiz were captured on video entering the Hernandez home about 15 minutes after Lloyd was shot.

The weapon in the slaying has not been recovered.

Hernandez is also being investigated in the July 2012 slayings of Daniel Abreu and Safiro Furtado in Boston’s South End, authorities have said.

Officials told the Globe in July that investigators believe Hernandez feared that Lloyd knew about the double homicide and might talk. No one has been charged with the South End killings.