(CBS) — The sister of the 18-year-old man shot and killed last week by Chicago Police officers said Friday that she wants to know why he had to die.

“We just want answers, the truth, that’s it,” Briana Adams said Friday during a news conference in the office of family attorney Michael Oppenheimer, hours after the Independent Police Review Authority (IPRA) released body-cam and dash-cam video.

Paul O’Neal was shot last Thursday during a foot chase, after smashing into police squad cars that were chasing his stolen Jaguar.

Adams said she will remember her younger brother as someone who was always smiling and always joking, was “best friend” to all he knew, had graduated high school, was ready to begin trade school and hoped to work for ComEd.

“Paul had goals,” she said.

The actual shooting of O’Neal, killed during a foot chase after police say he crashed a stolen vehicle into police cars, was not captured on a police body camera. But activist and family spokesman Ja’Mal Green said the video that shows what happens after the shooting is horrifying.

“After he was shot, he was placed in handcuffs and he sat there for a long time, dying,” Green said. “You also see one of the officers that was shooting at him, or the officer that shot him, walk it off and say, ‘What’s up, Jimmy?’ showing no remorse for what just happened.”

Oppenheimer said he believes the lack of footage of the actual shooting is a clear cover up by the department. He wants a special prosecutor appointed in the case immediately.

Green said that if the shooting had been caught on police cameras, more information would have likely been revealed.

“How can we hold these officers accountable when these body cameras that we use aren’t even working?” Green said. “This new technology, I understand there’s a learning curve, but we need stiffer penalties for officers who don’t have their body cameras working at all times.”

O’Neal was unarmed when shot. His family has filed a federal wrongful death lawsuit against the officers.