Four weeks after the former Patriots tight end was charged with murder and cut by the team, Belichick addressed the issue during a 22-minute news conference one day before his team opens training camp.
He expressed sympathy for the family of shooting victim Odin Lloyd, said the in-depth process of studying a player's background is "far from perfect" but wouldn't be overhauled, and took responsibility for bringing people to the team.
"The hundreds of players we've had through this program in the last 14 years, there's been a lot of good ones, a lot of real good ones," Belichick said. "We'll try to do a good job in bringing people into this organization in the future and try to learn from the mistakes that we've made along the way, of which there have been plenty."
At times, Belichick glanced down at notes and gripped both sides of the podium. He declined to answer some questions about Hernandez, saying he had been advised not to answer those about people involved in the legal case.
His relationship with team owner Robert Kraft continues to strengthen, he said.
Kraft has said he was "duped" by Hernandez. When Belichick was asked if he also had been "duped," he said he couldn't comment.
"I'm not trying to make this story disappear, but I respect the judicial process and have been advised not to comment on ongoing legal proceedings. I'm advising our players to do the same things," he said. "Ultimately, the judge or the jury will determine the accountability."
Quarterback Tom Brady and the team's other five captains are scheduled to speak with reporters on Thursday. The first practice is set for Friday.
The Patriots are eager to move on quickly from the Hernandez situation and any stain it leaves on the image of a team that has won three of its five Super Bowls in Belichick's 13 seasons as coach. Belichick usually doesn't address the media at training camp until it's begun.
"My comments are certainly not in proportion to the unfortunate and sad situation that we have here, but I've been advised to address the subject once, and it's time for the New England Patriots to move forward," he said. "Moving forward consists of what it's always been here — to build a winning football team, to be a strong pillar in the community and be a team that our fans can be proud of."
At a court hearing that overlapped with Belichick's news conference, prosecutors asked for more time to present evidence to a grand jury. 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.
The probable cause hearing was rescheduled for Aug. 22.
Hernandez has pleaded not guilty to murder in the shooting death of Lloyd, a 27-year-old Boston semi-professional football player whose body was found June 17 in an industrial park near Hernandez's home in North Attleborough.
"Our thoughts and prayers are with the family of the victim and I extend my sympathy really to everyone who has been impacted," Belichick said. "A young man lost his life. His family has suffered a tragic loss and there's no way to understate that."
Belichick said he was out of the United States when he learned of the criminal investigation and was "shocked and disappointed." He didn't say, in response to a question, if he had talked with Hernandez since the player's name was linked to it.
"This case involves an individual who happened to be a New England Patriot, and we certainly do not condone unacceptable behaviour and this does not in any way represent the way that the New England Patriots want to do things," he said. "As the coach of the team, I'm primarily responsible for the people that we bring into the football operation."
Hernandez dropped to the fourth round in the 2010 NFL draft because of character issues. Several teams took him off their draft board.
Belichick said "the fundamentals" of the Patriots' player evaluation process will stay the same as they've been since he became coach in 2000, but the team will work hard to do it better.
"We look at every player's history from the moment we start discussing it," he said, "going back to his family, where he grew up, what his lifestyle was like, high school, college experiences. We evaluate his performance, his intelligence, his work ethic, his motivation, his maturity, his improvement and we try to project that into our organization on a going-forward basis.
"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, not just at the beginning when they come in."
Asked if the Patriots will focus more on off-field issues when scouting college players, he said, "We have a process in place. Can it be improved? Can it be modified? It possibly can. We'll certainly look at it."
Belichick wouldn't answer a question about starting cornerback Alfonzo Dennard, who was charged with first-offence drunken driving after being pulled over in his car on July 11 in Lincoln, Neb., while on probation. He remains on the team.
Players are evaluated on "a case-by-case basis," Belichick said. "Whatever the circumstances are on any one individual, you'll have to make the decision based on an individual basis.
"With Aaron, we did what we felt was right for the football team."