She was shot and killed this past weekend, just after finishing her shift.
On Wednesday, prosecutors announced murder charges against four people.
Interim Superintendent Carter said the teens -- 19-year-old Trevor Breeland, 19-year-old Joseph Brooks, 18-year-old Jakwon Buchanan and 16-year-old Jaylan Frazier who is being charged as an adult - are charged with first degree murder as well as multiple counts of armed robbery, arson, burglary, possession of a stolen vehicle and unlawful use of a weapon.
Prosecutors also said Preston's shooting came at the end of a crime spree carried out by those suspects. That crime spree lasted almost two hours.
Exclusive video shows moments before CPD officer killed; 4 in custody for shooting, sources say
It started on Saturday morning around midnight on the 900 block of East 46th Street. A 33-year-old woman had just parked her car when she became the victim of an armed robbery.
A half-hour later, a Red Kia that was parked on the 4700 block of South Indiana was stolen.
Then, at 1:07 a.m., that Kia was used in the armed robberies of two women near 100th and Wallace.
Less than a half-hour later, there was another armed robbery after a man parked his car near his house at 91st and Merrill.
The crime spree ended with the shooting that killed Preston at 82nd and Blackstone.
Shortly after that, prosecutors said the robbery crew torched the Kia used in their spree. If convicted, the suspects could spend the rest of their lives in prison.
Slain Officer Areanah Preston's mother will accept her graduate degree from Loyola University
Slain CPD officer's mom will accept her graduate degree from Loyola
Preston was supposed to walk across a stage Saturday and accept her master's degree from Loyola University Chicago.
Instead, Preston's mother, Dionne Mhoon, will accept the degree on her behalf during the commencement ceremony, the university says. Preston was pursuing a master's of jurisprudence from the school.
"She was a student who was dynamic, intelligent, committed and a very driven person who wanted to make this world a better place," said Sara Block, academic director for child and family law programs at Loyola.
Block, who had Preston in her child welfare and juvenile justices classes, said the officer was trying to get the education she wanted while still performing her duties as a public servant. Preston would sometimes log in to her online classes from her patrol car while still in uniform.
Block said Preston had a balanced philosophy of prioritizing safety for individuals and communities while also prioritizing rehabilitation and understanding why people make the sometimes harmful choices they make.
"She was trying to understand how can these systems better meet those individuals' needs before they do something that's really harmful," Block said. "It was a unique perspective as a law enforcement officer, and that was really evident in how she viewed the issues."
Four teenagers have been charged in connection with Preston's slaying. After the suspects appeared in court Wednesday, Mhoon told reporters that the family was looking forward to a large party celebrating Preston's and other family members' academic accomplishments.
"Our university community is shocked and saddened by her tragic passing," a Loyola spokesperson said. "She will be remembered by her faculty and classmates for her kindness, intellect and commitment to service. We wish to express our deepest condolences to the Preston family and to all those whose lives she touched."
Preston previously got her bachelor's degree in criminal justice and law enforcement administration from Illinois State University.
That's where she met professor Charles Bell, who said Preston was a "very engaged, very vocal student, very respectful of others' opinion and just very passionate about making a difference and showing young people that policing is a profession that can make a difference in the community."
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The Sun-Times Media Wire contributed to this report.