UPDATE: A Chattanooga teenager facing first degree murder charges in connection to a quadruple shooting will go on trial in September despite the fact that one of the key witnesses in the case was found dead. 

Cortez Sims, 19, appeared in court Thursday for a hearing before Judge Barry Steelman.

"He smiled like he don't care, like he hasn't done anything. His family doesn't want justice," Sebrina Robinson said. 

Robinson says Sims' demeanor in the courtroom doesn't reflect the seriousness of the charges against him. 

She comes to every hearing wearing a shirt bearing her daughter's picture. 

"Now I want justice for my daughter, for Bianca and for baby Zoey," she added. 

Robinson's daughter, Talitha Bowman, 20, was killed in 2015 when police say the the 17 year old Sims burst into a College Hill Apartment and opened fire. 

Three others were hurt in the shooting including Zoey Horton, 1.

Her mother Bianca was a key witness in Sims' trial and was set to testify in September until she was found shot to death last month. 

It's still unclear if her testimony played a role in her death but Mayor Andy Berke previously told Channel 3 her death will not hurt this case. 

"She has testified and her testimony is recorded in a way that is going to keep that case going forward," he said. 

Despite fears for her safety and the safety of her family, this mother still pushes forward keeping the memory of both young women alive.

"I've been threatened. I have to keep my head up. I have to stay in court. I have to get justice for my daughter," Robinson said. 

Sims will be in court for another hearing on July 21st. He will go on trial on September 27th.

PREVIOUS STORY: A teen facing first-degree murder charges will be in court Thursday. 

Cortez Sims is being tried as an adult in the quadruple shooting from 2015. He was 17 at the time. 

The shooting left one woman dead, paralyzed a baby from the chest down and hurt two others. 

Police say Sims burst into a College Hill Courts apartment and opened fire before taking off. 

That prompted a search by multiple state and local agencies. He was arrested days later in Knoxville. 

Investigators are trying to figure out if the murder of one of the witnesses set to testify in Sims' case is connected to him. 

Bianca Horton, the mother of the baby that was seriously injured, was going to testify in the upcoming September trial. 

Channel 3 will be in courtroom this morning and will bring you updates as this story develops.