Kraft said the Patriots had no knowledge of Hernandez's actions when he wasn't at Gillette Stadium.
"When he was in our building, we never saw anything where he was not polite,'' Kraft said. "He was always respectful to me.
"You can be sure we'll be looking at our procedures and auditing how we do things."
It was Kraft's first business day back in the United States after a trip to Europe. He was there when he first learned of Hernandez being charged with the murder of Odin Lloyd. Kraft said it was "important that our fan base hear directly from our organization" in a face-to-face setting.
"My heart goes out to the Lloyd family," he said. "I feel bad that someone connected to our organization is connected to this."
Kraft explained that he had to be limited in his remarks because of the ongoing criminal investigation as well as other potential civil proceedings, and was speaking against the advice of his general counsel.
Kraft said the Patriots did not know Hernandez would be facing a murder charge when they released him shortly after his arrest.
In other Hernandez news yesterday, a Massachusetts judge says he will release impounded search-warrant materials in the murder case.
Attleboro District Court Judge Daniel O'Shea said the material will be released at 2 p.m. today.
Motions to unseal the material were filed by the Patriot Ledger and Taunton Gazette newspapers and their parent Gatehouse Media, supported by the Associated Press, and by the Boston Globe.
Hernandez has pleaded not guilty to the murder charge in the June 17 fatal shooting of Lloyd.
Two other men are facing lesser charges. One of the men, Ernest Wallace, of Miramar, Fla., was ordered held without bail after pleading not guilty.
Prosecutors say Wallace, 41, and another man, Carlos Ortiz, were with Hernandez when they drove with Lloyd to an industrial park, where he was killed.
Authorities say Hernandez orchestrated the killing because he was upset at Lloyd for talking to certain people at a nightclub a few days earlier; they have not said who fired the fatal shots.
A federal judge in Philadelphia ordered the NFL and former players to negotiate over whether claims of concussion-related injuries will move forward in court or in arbitration.
U.S. District Judge Anita B. Brody had planned to rule July 22 in a legal fight involving about 4,200 former players and the league.
However, she told the two sides to try to resolve how the case will proceed by going through mediation with retired U.S. District Judge Layn Phillips. The retirees want the right to sue the league, while the NFL insists the claims fall under the collective bargaining agreement, and should be resolved in arbitration.
* A former NFL player is suing the Washington Redskins and former assistant coach Gregg Williams, saying a career-ending knee injury is the result of a bounty program where Redskins coaches encouraged players to intentionally injure opponents.
Barrett Green, a linebacker who played for the Detroit Lions and the New York Giants between 2000 and 2005, said a career-ending knee injury during a Giants-Redskins game on Dec. 5, 2004, was the result of a bounty program and a "unusual, outrageous, and an obvious cheap shot."
After leaving Washington, Williams was the defensive coordinator for the New Orleans Saints and was considered the mastermind behind the bounty scandal that led to unprecedented sanctions from the NFL. He was suspended for 1 year by the league and is now a senior defensive assistant with the Tennessee Titans.
The lawsuit also names former Redskins player Robert Royal, the tight end who hit Green.
* New York Giants wide receiver Victor Cruz signed a 5-year contract extension that runs through the 2018 season. It is reportedly worth $43 million.