Owens said he could not discuss an inmate's medical history because of privacy laws. He said the jail prescribed two of the drugs for Heredia. The Doxepin, he said, she obtained from another inmate.
The explanation did not satisfy Heredia's mother, Carmen Feliciano, who questioned why jail authorities did not send her daughter to nearby Cooper University Hospital after an earlier fainting spell.
She said Thursday that she has retained a lawyer and plans to sue the county.
"Just because someone's a prisoner doesn't give them the right to treat them like animals," Feliciano said, rocking back and forth, tears in her eyes. "Everybody makes a mistake. . . . She could have still become somebody."
Jail officials did nothing wrong, Owens said.
Inmates are observed when they take medications, Owens said, but some conceal the pills to bypass the screening.
"She admitted to taking another inmate's medication," Owens said of Heredia.
The cocktail of drugs that Heredia had taken is used as an antidepressant, as treatment for drug addiction, and as a way to manage pain. If not prescribed properly, the combination can be lethal.
Heredia, relatives said, was not on any medication that they knew of during her time in jail.
Feliciano said she last saw her daughter, who appeared healthy, on Oct. 3 during a visit with Heredia's 6-year-old daughter, now in Feliciano's custody.
"She was fine, she was healthy, she just said she was thirsty," Feliciano said.
Later that month, Feliciano said, jail officials said her daughter turned down the weekly visit. The next day a court hearing was postponed, apparently because Heredia was ill, Feliciano said. Days later, Heredia died.
Feliciano said that besides the cause of death she had not received any explanation from the county as to what happened.
A warden came to her home to report the death and said only that her daughter had fainted in the shower a few days prior, Feliciano said.
"If she fainted, why was she not put in the hospital?" Feliciano asked. "Cooper is right next door."
Authorities have said Heredia was transferred to the jail's medical wing after complaining of leg pain caused by a prior car accident. Feliciano said her daughter, who lived with her, was never in an accident.
An inmate who called Heredia's family said Heredia fell from her bed, convulsing, and vomiting as her cellmate screamed for help, Feliciano said.
Heredia had a history of drug use and dealing, according to court documents. Last year, she was convicted of distributing narcotics. Other drug arrests date to 2010.
Angel Cordero, a community activist who knew Heredia from his alternative education program, Community Education Resource Network (CERN), has said Heredia's death calls for an investigation, noting that the jail has a history of neglecting or abusing inmates.
Cordero spent nine months in the jail in 1980 following a narcotics conviction.
"I had to beg for Tylenol to help my migraines. I passed out from the pain. That was 1980; nothing's changed," Cordero said. "And now a 23-year-old mother is dead."
The jail - with a capacity to house 1,083 inmates according to a 2007 analysis - is currently crowded with 1,535 inmates.
The jail is under court order to improve conditions, including the overcrowding.