Chicago (CBS) — Colleagues, strangers and officers all stood in the rain Sunday evening as flashing blue lights led the body of Officer John Rivera to the funeral home.

Jennifer Navarro said she and 23-year-old Rivera first became friends while attending Harold Washington College. The two of them shared a lot of great times together.

“We used to love going to this karaoke bar in Chinatown called Number 18. That was our spot,” Navarro said. “When he smiled, he glowed.”

That glow is now gone.

Navarro said she was devastated when she heard about Rivera’s death Saturday morning.

“Part of my heart literally felt like it was taken away,” she said.

Police say Officer Rivera was a part of the force for 22 months. Footage from a murder scene at 84th and Sangamon Friday showcases one of the final times Rivera would wear the uniform.

The 23-year-old’s uncle is retired CPD chief of internal affairs Juan Rivera.

The rookie cop grew up in Chicago’s Hegewisch neighborhood on the city’s Far South Side.

He attended Mt. Carmel before transferring to Brother Rice where he graduated in 2013.

The school’s administration said in a statement, “We express our deepest condolences to his family. John is remembered as a nice, polite, and soft spoken young man.”

CPD has assigned 12 detectives to the case.

Officers believe Rivera’s death was the result of a mistaken identity. A gunman approached his car in River North and opened fire.

“John’s a sweetheart. He’s an angel. Why would someone just want to take his life away like that?” Navarro said. “He had a whole life ahead of him.”

Services for Officer Rivera begin Thursday with a visitation 3 to 9 p.m. at Elmwood Chapel at 112th and Ewing. The following day, a funeral mass will be held at 10 a.m. at the Church of Annunciata, 11128 S. Avenue G. His burial will be private.