Officials believe the high-capacity magazines used by the suspect in last month’s mass shooting at a Boulder King Soopers were sold legally, Boulder County District Attorney Michael Dougherty revealed at a news conference Thursday morning. prosecutors expect to file more charges against him.

The press conference was held exactly a month after the massacre.

Authorities say 22-year-old Ahmad Al Aliwi Alissa entered the King Soopers at 3600 Table Mesa Drive in south Boulder on March 22, and began firing just after 2:30 p.m. During the massacre, customers, employees and one Boulder police officer were killed.

Dougherty confirmed Officers Bryan Capobianco and Pam Gignac were the first to enter the store along with Officer Eric Talley. Talley was killed within seconds of entering the store, Dougherty said. 

A second wave of officers entered the store within 30 seconds of Talley being killed.

Dougherty said the latest charging document in the case, filed Wednesday, lists counts for the murder of victims in the order in which officials believe the suspect killed them. Likewise, the document lists the attempted murder charges against the suspect in the order in which prosecutors believe events unfolded. 

Officials estimate that there were at least 115 people in store and at least 25 in the parking lot at the time of the attack.

The suspect was shot in the thigh exchange of gunfire with responding officers. He stripped most of his clothes off and put his weapon down before walking backward toward police to surrender, according to the arrest affidavit.

He received treatment for his gunshot wound at a local hospital before authorities brought him to the Boulder County jail the day after the massacre.

Officials have not indicated any possible motive for the attack.

After the shooting, memorials for victims sprang up at a makeshift fence surrounding the King Soopers and around Boulder. The city’s grief spilled over into public vigils and memorial services in the days following.

“The response since March 22 has been absolutely incredible,” Dougherty said. “Our community has come together and united for all the victims in response to this crisis. That’s why I believe this community will move forward together.”

Dougherty said that each family has a victim advocate assigned.

He said last weekend through Monday, any victims, family members and police officers who wished to were allowed “site visits” to go into the King Soopers as part of their healing process.

Prosecutors have sought to file more than 40 additional charges against Alissa, which would bring the total number he faces up to 54, according to a motion filed Wednesday. 

Alissa was first charged with 10 counts of first-degree murder and first-degree attempted murder of a police officer in Boulder County district court.  

The motion seeks to charge the alleged shooter with an additional 33 counts of first-degree attempted murder –20 of them for attempting to kill police officers, according to the court document. 

Dougherty said he expects additional charges for attempted murder and crimes of violence to come later.

“They represent victims who have a right to be heard and supported, so that’s why these additional charges are being filed, to recognize all the victims in this case,” Dougherty said.

Additionally, the shooter has been charged with 10 counts of possession of a prohibited high-capacity magazine while committing a felony and one count of first-degree assault. 

A total of 10 magazines were found either on the suspect or in his car, according to Dougherty. He said officials believe the magazines were sold legally, but he declined to provide more information Thursday about where or how the suspect may have acquired them. 

The court document did not specify how many rounds were within the alleged shooter’s magazines, and Dougherty declined to provide information about the specific capacity of each magazine found, but Colorado state law prohibits more than 15 rounds per magazine. 

Some of the attempted murder charges include two counts for one survivor: One charge for intent to kill after deliberation, and a second for showing extreme indifference to human life and knowingly engaging in conduct that created a risk of another person’s death. 

Dougherty said sentences for the charges against the suspect would be elibible to run consecutively. The first-degree murder charges each carry a maximum penalty of life in prison without the possibility of parole. The attempted murder charges each carry a possible sentence of 16 to 48 years, while the counts for using a prohibited high-capacity magazine while committing a felony or crime of violence each have possible sentences between six and 18 months, Dougherty said.

The case has a status hearing scheduled for May 25. 

The 10 victims of the shooting were identified as: Denny Stong, 20; Neven Stanisic, 23; Rikki Olds, 25; Tralona Bartkowiak, 49; Teri Leiker, 51; Officer Talley; Suzanne Fountain, 59; Kevin Mahoney, 61; Lynn Murray, 62; and Jody Waters, 65.

This story has been updated to correct the total number of new attempted murder charges filed against the suspect.