CENTENNIAL — A journey of nearly 1,000 days ends Tuesday, when a judge and two teams of lawyers begin choosing the jurors who will decide justice in the Aurora movie theater attack, one of the worst mass shootings in American history.

While juror candidates don’t arrive until the afternoon, people started entering the Arapahoe County courthouse well before the 9 a.m. check-in for attorneys in the case. Media and satellite trucks filled rows of the parking lot Tuesday morning, and security officers outside the courthouse shouted “No cameras of any kind!” to those lining up to go into the building.

The first wave from a pool of 9,000 potential jurors will arrive at the courthouse about 1 p.m. They will listen to some instructions, fill out a lengthy questionnaire and then go home. The whole process might take only a couple of hours.

For a month, jury selection will inch along like this, with waves of jurors arriving in the morning and afternoon to complete questionnaires. More detailed questioning of potential jurors will begin in mid-February.

“We deeply appreciate your participation in this important aspect of our democratic society,” Judge Carlos Samour will tell the jurors Tuesday, according to his prepared remarks. “Without you, we could not have jury trials of the system of justice our nation enjoys.”

Tuesday’s start of jury selection comes 914 days after the July 2012 attack on the Century Aurora 16 movie theater, in which 12 people were killed and 70 others wounded. Prosecutors are seeking the death penalty against James Holmes, while his attorneys contend that he was insane and should be committed to a mental health institution.

It will likely be late May or early June before a jury is seated. So, while Tuesday marks the end of one journey, those impacted by the attack know the day also marks the beginning of another.

“We’ve all been to therapists and have talked to our families and have our support groups, so we’re prepared,” said Marcus Weaver, who was shot in the arm and whose friend, Rebecca Wingo, died in the attack. “It’s gonna be quite the journey.”

The Associated Press contributed to this report.