Aréanah Preston’s mother will accept her college degree on her behalf after her daughter was shot and killed in a robbery last weekend.

The Chicago police officer was set to walk across the stage on Saturday to accept her master’s degree from Loyola University Chicago, the Chicago Sun-Times reported. Preston was pursuing a master’s in jurisprudence.

“She was a student who was dynamic, intelligent, committed and a very driven person who wanted to make this world a better place,” Sara Block, the academic director for child and family law programs at Loyola, said.

Block shared Preston attended her child welfare and juvenile justice courses while working as a police officer. She would sometimes log into classes from her patrol car.

“She was trying to understand how can these systems better meet those individuals’ needs before they do something that’s really harmful,” Block said about Preston’s commitment to rehabilitation and understanding of the communities she served. “It was a unique perspective as a law enforcement officer, and that was really evident in how she viewed the issues.”

Four teenagers were charged with first-degree murder and were denied bail on Wednesday. The teens were also charged with armed robbery, burglary, motor vehicle theft and other offenses connected to incidents on Friday and Saturday, CBS reported.

Preston was shot around 1:40 a.m. Saturday during a robbery spree, the police said. She was heading home from work when duty called.

“We’re missing someone, and it’s always a hole that won’t be filled,” Preston’s mother, Dionne Mhoon, told reporters outside the courtroom on Wednesday, according to NBC. “The hole in our hearts will never be closed.”

Preston’s friends and family gathered at a vigil held on Tuesday at the Fifth District police station, where she served. Hundreds of people were in attendance.

“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.”