HOUSTON – Houston activist Quanell X claims the 21-year-old suspect in the death of Nassau Bay police Sgt. Kaila Sullivan is severely mentally ill and “panicked in a traffic stop,” the night the sergeant was killed.

The activist held a press conference Thursday, flanked by Tavores Henderson’s grandmother, to call on the Harris County District Attorney’s Office to reconsider Henderson’s capital murder charge and to denounce the $150,000 bond faced by his mother, Tiffany.

RELATED: After 2-day manhunt, Tavores Henderson captured; faces capital murder charge

Quanell X said Henderson took “serious, psychotropic medications” since the age of 6 and had stopped taking them around the time of Sullivan’s death. He said he had proof that the day before the sergeant was killed, Tiffany Henderson had tried to get her son admitted to a psychiatric hospital for treatment, but he escaped from the facility after a psychiatrist had examined him.

“The young man was very resistant because he was off of his meds," Quanell X said. He said Henderson had been diagnosed with paranoid schizophrenia and bipolar disorder.

“This young man is not a cold-blooded killer, he’s not a cold-blooded murderer. He made a sick, sad mistake from a sick mind," Quanell X said.

He went on to say the DA’s office was aware of Henderson’s mental illness before his charge was upgraded to capital murder.

“You want to punish him but you don’t want to help him,” Quanell X said. “He panicked in a traffic stop."

Tiffany Henderson is accused of helping her son hide from police for two days before he was eventually caught. She and her boyfriend, Geoffrey Wheeler, each face felony charges of hindering the apprehension of a fugitive. Tiffany Henderson is in custody on a $150,000 bond, which Quanell X called “political pandering” by the judge and the DA’s office. He claimed prosecutors and the judge were swayed by the outrage from law enforcement officials and the community.

In a previous interview with KPRC 2, Tiffany Henderson also said Henderson suffered from mental health issues since he was a child. She said his mental health worsened when her mother died last year. She also said he had stopped taking his medicine for a year.