The mother and sister of Decarlos Brown, the suspect in the fatal stabbing of a Ukrainian woman on Charlotte light rail, say that he struggled with mental illness for years after being released from prison and that he claimed there was a “material” in his body that controlled him. 

Brown, 34, was arrested on Aug. 22 after police say he stabbed 23-year-old Iryna Zarutska three times while riding the Lynx Blue Line in Charlotte, according to an affidavit obtained by ABC News.

In audio recordings of a conversation between Brown and his sister several days after his arrest, obtained by ABC News, Brown maintains that he has “material” in his body that caused him to attack Zarutska.

“Make sure it was me that did it, not the material. And I’m telling you, the material did it,” Brown said, according to the recordings.

The suspect can be heard telling his sister that he did not “even know the lady at all.”

“I never said not one word to the lady at all. That scary, ain’t it? So, like, why would somebody stab somebody for no reason?” Brown can be heard telling his sister.

Brown has been charged by the U.S. Attorney’s Office in the Western District of North Carolina with committing an act causing death on a mass transportation system, which could make him eligible for the death penalty, the Department of Justice said Tuesday.

“This brutal attack on an innocent woman simply trying to get to her destination is an attack on the American way of life. Of course, crimes like this affect the victim the most — Iryna deserves justice, and we will bring justice to her and her family,” U.S. Attorney Russ Ferguson said in a statement on Tuesday.

Brown’s sister and mother said they noticed a difference in his behavior following his incarceration, which ended in 2020, and that it got worse over the three years since he was released.

Brown’s mother, Michelle Dewitt, said her was son was diagnosed with schizophrenia and after his time in prison, he “was different.”

“He wasn’t the normal Carlos, the fun Carlos,” Dewit told ABC News in a separate interview.

The 34-year-old suspect has a criminal record including larceny and breaking and entering charges. He also spent five years in prison for robbery with a dangerous weapon starting in 2015, according to the North Carolina Department of Adult Correction. He was also arrested this year for misusing the 911 system, according to court records.

In total, Brown has been charged 14 times in the past, including an arrest in January, but was “still on the streets” leading up to the attack, North Carolina FBI Special Agent James Barnacle Jr. said on Tuesday.

Brown’s mother told ABC News that after her son had been released from prison in 2020 after serving time for armed robbery, “he was different” and began showing violent behavior like slamming doors and yelling in her face. While he was living with her, he would also walk around the home and talk to himself, Dewitt said.

Dewitt said her son had been diagnosed with schizophrenia and had been given medication, but she said he refused to take it.

Dewitt said she grew increasingly concerned about the safety of her and her husband and took Brown to a mental health hospital. She said the hospital told her they didn’t have enough room to admit Brown and because he wasn’t threatening to hurt himself, they couldn’t take him.

She said the hospital told her, “You can’t make a person come” to the facility.

Dewitt said she was left with no option but to go to court to file with a magistrate a petition for her son to get help. As a result of that, she said, a mental health facility kept Brown for 14 days, but eventually released him back to her and her husband’s care.

She said she had hoped to keep Brown on a schedule and to create a routine for him, but it didn’t work after he stopped taking his medication. 

“We’re just not going to do it anymore,” Dewitt said of how she and her husband were feeling at the time. “We dropped him off at a shelter.” 

The mother identified that shelter as the Roof Above Lucille Giles Men’s Shelter in Charlotte, which is run by a nonprofit organization called Roof Above. 

ABC News reached out to the shelter, but no one from the shelter was immediately available to comment. 

In recent months, Dewitt said she has seen her son on the street, walking up and down, and her younger daughter would see him riding the bus.

When he was arrested in January for misusing 911, she said he kept saying “he had a chip in him,” and that “the police put it in him.”

According to the affidavit from Brown’s arrest in January, officers were responding to a welfare call when Brown told them he believed someone gave him a “man-made” material that controlled what he ate and how he walked and talked.

Brown’s next court appearance in is scheduled for Sept. 19, according to court records. It is unclear whether Brown has an attorney who can speak on his behalf.

Brown’s sister, Tracey Brown, said she is not trying to excuse her brother’s alleged actions.

“At the end of the day, I’m not making any excuse for what happened,” she said. “I am saying that if he had the proper care this wouldn’t have happened.”