In December 2021, Rittmanic, 49, and then-Officer Tyler Bailey were shot after approaching a man who was wanted on a warrant for his arrest.
Prosecutors allege Darius Sullivan shot the officers as they confronted him at his hotel room door.
Sullivan and his girlfriend Xandria Harris are charged with murder and attempted murder.
The couple was allegedly in the hotel room with their three young children. Sullivan is also charged with endangering the lives of children. Harris will be tried separately.
Rittmanic and Bailey had been called to the Comfort Inn off Route 50 that night for a report of dogs barking, left in a car on a cold night outside the hotel. Once there, they discovered Sullivan, who was staying at the hotel, had a warrant out for his arrest.
Kankakee County State's Attorney Jim Rowe told jurors they would see video from police body cameras and hear Rittmanic's last words.
Sullivan's defense attorney told jurors the videos don't tell the whole story, and that Sullivan was defending his family that night, thinking someone was breaking into his hotel room.
Bailey was seriously injured but survived. Rittmanic was honored by officers and civilians at her funeral and was buried at the Abraham Lincoln National Cemetery.
Jurors heard from Rittmanic's sister, who tearfully identified her and testified she saw her two days before Christmas this year. She confirmed Rittmanic was a sergeant with the Bradley Police Department.
A hotel front desk worker testified that a colleague called 911 about the dogs left in the car, and, after two officers arrived, hearing shots. She said she called 911 and then the staff went into lockdown.
Jurors saw video from the hotel hallway which shows some confrontation, then someone on the ground and someone running.
"I was able to see movement in the hallway and eventually a male walk to the elevator who wasn't an officer," said former hotel worker Stephanie Skraeutenas.
Officer Bailey is expected to testify at some point during this trial, which is expected to last two weeks.