The 26-year-old was working at Boise Towne Square mall in Boise, Idaho as a member of the security team at the time of the incident on 25 October.
According to her family, Acker ran toward the suspect in an effort to stop him and save those at the mall – something that likely saved numerous lives.
KKTV News 11 reports that four people were injured in the shooting in addition to the two fatalities – Acker and 49-year-old Roberto Padilla Arguelles.
In a statement, the Boise Police Department said: “Evidence indicates the suspect was contacted by a security officer on the first floor of the building near a department store on the west side of the building.