Hernandez was in court for what was supposed to be a probable cause hearing, but prosecutors said the grand jury is still considering the evidence against him.
Judge Daniel O'Shea rescheduled the probable cause hearing for Aug. 22, after considering defense objections to a delay. Hernandez will be held without bail until then.
Hernandez has pleaded not guilty to murder in the death of Odin Lloyd, a 27-year-old Boston semi-professional football player whose body was found June 17 in an industrial park near Hernandez's home. He had been shot five times.
Bristol County Assistant District Attorney William McCauley said additional evidence includes boxes of ammunition found at a condominium Hernandez leased and a magazine clip for a .45-caliber Glock in a Hummer registered to him. Police say Lloyd was killed with a .45-caliber gun. McCauley said the box had Hernandez's fingerprints on it.
Hernandez attorney James Sultan objected to the delay, saying his client has already been jailed for four weeks and that the district attorney could have waited to bring charges, but chose to go ahead last month.
"He made it sound like a slam dunk case," Sultan said.
Outside court, another of Hernandez's attorneys, Charles Rankin, said he's confident Hernandez will be exonerated and his attorneys were "extremely disappointed" that prosecutors weren't prepared to present their case. Hernandez's girlfriend, Shayanna Jenkins, was in court for the hearing but said outside the courthouse that she had no comment.
Also Wednesday, O'Shea ruled in favor of media organizations including The Associated Press and ordered the release of two arrest warrants and other search warrants and materials that have been impounded. They'll be released at 3 p.m. Thursday if no one appeals.
Prosecutors say Hernandez orchestrated Lloyd's killing because he was upset at him for talking to people Hernandez had problems with at a nightclub a few days earlier.
They say Hernandez and two associates, Ernest Wallace and Carlos Ortiz, drove with Lloyd to the North Attleborough industrial park. Authorities have not said who fired the shots, but documents filed in Florida - and released since Hernandez's last court appearance - paint the former Patriot as the triggerman. According to the records, Ortiz told police that Wallace said Hernandez fired the shots.
Hernandez was kicked off the team soon after his arrest and New England Patriots coach Bill Belichick broke his silence Wednesday, saying the Patriots will learn from "this terrible experience," and that it's time for New England to move forward.
"We'll continue to evaluate the way that we do things, the way that we evaluate our players and we'll do it on a regular basis," Belichick said. "I'm not perfect on that, but I always do what I think is best for the football team."
Wallace and Ortiz also are facing charges. Wallace pleaded not guilty to a charge of being an accessory to murder after the fact. Ortiz has pleaded not guilty to a gun charge.
Warrants released Tuesday in Hernandez's hometown of Bristol, Conn., show police found ammunition, a gun box and documents tied to Ortiz and Wallace at Hernandez's uncle's home.
The warrants were used to search that home, where Ortiz said he lived; an apartment also linked to Ortiz; and a rental car police say was used by Wallace and Ortiz to return to Connecticut the day after the shooting.
The items seized from the home included clothes, Correction Department documents linked to Ortiz and Wallace, a plastic gun box and two boxes of .38-caliber ammunition.
Bristol police also have been investigating a possible link to a 2012 fatal shooting in Boston, and earlier said they had seized an SUV wanted in that investigation from the uncle's home.