A judge ruled today the 21-year-old Colorado man accused of gunning down 10 people at a supermarket in Boulder earlier this week will be held without bail.

Ahmad Al Aliwi Alissa, from the Denver suburb of Arvada, has remained in custody at the Boulder County Jail since police arrested him at the King Soopers grocery store on Monday. He was charged with 10 counts of first-degree murder and one count of first-degree attempted murder on a police officer.

Alissa appeared at the brief hearing wearing a mask. He spoke only to respond “yes” to a question from the judge and did not enter a plea to the charges, which will come later in the judicial process. Boulder County District Attorney Michael Dougherty said authorities planned to file more charges, but did not elaborate.

Kathryn Herold, the defense lawyer for Alissa, asked for a mental health assessment “to address his mental illness,” but provided no details about what he might suffer from.

The suspect’s family has told investigators they believed Alissa was suffering some type of mental illness, including delusions.

Relatives described times when Alissa told them people were following or chasing him, which they said may have contributed to the violence.

Former high school wrestling teammate Angel Hernandez said that Alissa would act strangely sometimes.

“He would say, ‘Did you see that? Did you see that?’” Hernandez recalled. “We wouldn’t see anything. We always thought he was messing with us.”

Alissa had bought a Ruger AR-556 pistol – which resembles an AR-15 rifle with a slightly shorter stock – on March 16, six days before 10 people, including a police officer, were killed at the supermarket, according to an arrest affidavit. Investigators did not immediately disclose where the suspect purchased the weapon.

Alissa was taken into custody after suffering a bullet wound to a leg. He was taken to a hospital for treatment before being transferred to jail.

Last night, hundreds of mourners gathered in downtown Boulder to hold a candlelight vigil in remembrance of the 10 victims.

One of the victims was veteran Boulder Police Officer Eric Talley. The others were identified as Denny Stong, 20; Neven Stanisic, 23; Rikki Olds, 25; Tralona Bartkowiak, 49; Suzanne Fountain, 59; Teri Leiker, 51; Kevin Mahoney, 61; Lynn Murray, 62; and Jody Waters, 65.

Investigators have not established a motive for the attack.

Alissa’s next hearing will not be scheduled for another two to three months, at his attorney’s request, to allow the defense team to evaluate his mental health and evidence that is being collected by investigators.