Hernandez, 25, has been charged with the murder of 27-year-old Odin Lloyd, a former semiprofessional football player. Lloyd, who was killed on June 17, 2013, had been dating the sister of Hernandez's fiancee.
More than 100 prospective jurors were brought in on Friday to the Fall River Justice Center in Fall River, Mass. The court plans on bringing in three groups of 125 people for the selection process the first day and more than 1,000 total over a three-day period, according to the Associated Press. Of that group, 18 will eventually be selected to sit on the trial.
"I want to stress that the charges in the indictment are merely allegations — claims if you will," Bristol County Superior Judge Susan Garsh told the potential jurors.
The prosecution contends that Hernandez picked up Lloyd from his Boston home with two other men and took him to an industrial park in North Attleborough, Mass., not far from where the ex-Patriot lived, and shot him to death.
Carlos Ortiz and Ernest Wallace, the two other men charged in the killing, have also pleaded not guilty and will be tried separately.
Hernandez was arrested on June 26, 2013, shortly after he was released by New England after three seasons with the Patriots, who selected him in the fourth round of the 2010
The court has banned all persons from wearing any Patriots or NFL related clothing to the trial.
The jury selection process, which began with potential jurors filling out questionnaires, is expected to take more than a week. The trial itself, another six to 10 weeks.
The prosecution has listed almost 300 people as potential witnesses, including Patriots owner Robert Kraft, Coach Bill Belicheck and Hernandez's fiancee, Shayanna Jenkins, for whom the prosecution has petitioned the judge to grant immunity.
Hernandez also faces other murder charges in Boston, where he's been accused of killing two men after one spilled a drink on the former Florida player.
The Associated Press contributed to this report.