Viameri Santana-Berrios, 27, from the 2700 block of Helen Street was arrested on Thursday.
She is charged with Murder, Criminal Conspiracy, Endangering the Welfare of a Child and related offenses in the murder of 9-month-old Milton Galarza-Rojas.
Oscar Sanchez-Rivera, 24, of the 1900 block of E Market Street in Bethlehem, was arrested in April on the same charges.
It was back on July 26th when medics, responding to a 911 call at 2:30 a.m. in the 4500 block of North 7th Street, found the baby non-responsive.
He was rushed to St. Christopher's Hospital where he was pronounced dead just after 3:00 a.m.
The medical examiner determined the cause of death was heroin and cocaine intoxication.
