A witness at a certification hearing Thursday said the juvenile suspect in the killing of 17-year-old Mark Brandon Dominguez should be tried as an adult.

Yolanda Ybarra, mother of the slain teen, sat inside the South Austin courtroom, listening as a clinical and forensic psychologist testified that the 16-year-old suspect would be a continued threat for future violence.

“One of the factors I am asked to consider is treatment and amenability, how likely is this person to benefit from the programs and treatment available in the juvenile justice system,” Stephen Throne, Ph.D., said. “I consider him a future risk for violent behavior."

Testimony at the hearing revealed a troubled history for the troubled teen.

He was on probation for a pair of drug arrests at the time of crime. In the last year, he was subjected to 28 drug tests, failing 27 of them for marijuana.

Police records showed the suspect is a documented Sureños 13 gang member, but the teenager denies any involvement.

Other testimony at the hearing claimed the 16-year-old made violent threats against his peers and detention staff after his arrest.

The suspect's attorney, Jon Evans, says placing any teen in the adult criminal justice system is an injustice.

"I think it's pretty well documented the adult system offers nothing as far as rehabilitation treatment is concerned," Evans said.

Dominguez was killed in January outside of his South Austin home. The 17-year-old went outside in the overnight hours to investigate what he and his brothers suspected to be a car break-in.

His suspected killer has been charged with murder, attempted murder and aggravated assault.

The suspect will remain in custody at least through the end of the certification hearing. The next hearing for this case is scheduled for next Thursday at 11 a.m.