Updated

Boulder County District Attorney Michael Dougherty filed 43 more charges against Ahmad Al Aliwi Alissa Wednesday, nearly a month after the 21-year-old allegedly went on a shooting rampage in a King Soopers supermarket that left 10 people dead

Alissa was already charged with 10 counts of first-degree murder and one count of attempted murder in the attack. 

He now faces 33 additional counts of attempted first-degree murder, one count of first-degree assault and 10 counts of felony possession of a prohibited large-capacity magazine, according to an amended complaint filed by prosecutors on Wednesday.

BOULDER SHOOTER WAS ALLEGEDLY 'CHUCKLING' TO HIMSELF AS HE MURDERED 10 PEOPLE: REPORT

District Attorney Dougherty will give an update on the new charges and the ongoing prosecution Thursday morning at 10 a.m.

Ahmad Al Aliwi Alissa, 21, appears before Boulder District Court Judge Thomas Mulvahill at the Boulder County Justice Center in Boulder, Colo. on March 25, 2021.

Ahmad Al Aliwi Alissa, 21, appears before Boulder District Court Judge Thomas Mulvahill at the Boulder County Justice Center in Boulder, Colo. on March 25, 2021.

Alissa is accused of opening fire at the supermarket on the afternoon of March 22 with a Ruger AR-556 pistol, which looks similar to an AR-15 rifle. 

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Officer Eric Talley led a team of police into the store just two minutes after the shooting began and engaged in a shootout with Alissa. 

Talley was struck in the head and died. Nine other people were also killed during the shooting: 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 Jodi Waters, 65.

A child lays flowers near the police car of officer Eric Talley who died Monday responding to a call where a gunman opened fire on people in a King Soopers grocery store in Boulder, Colorado, U.S. March 24, 2021. 

A child lays flowers near the police car of officer Eric Talley who died Monday responding to a call where a gunman opened fire on people in a King Soopers grocery store in Boulder, Colorado, U.S. March 24, 2021.  (REUTERS/Kevin Mohatt)

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Alissa's lawyer, public defender Kathryn Herold, said in the accused mass shooter's first court appearance on March 25 that her client needs a mental health review. 

"Our position is we cannot do anything until we are able to fully assess Mr. Alissa’s mental illness," Herold said in court. 

The Associated Press contributed to this report.