PHILADELPHIA (CBS) – A couple caring for a nine-month-old infant who died after having difficulty breathing has been charged with murder.

Oscar Sanchez-Rivera, 24, and his girlfriend, Viameri Santana-Berrios, 27, were arrested after Santana-Berrios’ nephew’s son died while they were caring for him.

Police were called to the residence on North 7th Street on July 26, 2011 at 2:36 p.m., where they found the child unresponsive in the basement. He later died at St. Christopher’s Hospital, and a medical examiner determined the cause of death to be heroin and cocaine intoxication and the manner of death to be murder.

Sanchez-Rivera, of the 1900 block of East Market Street, and Santana-Berrios, of the 2700 block of Helen Street, are charged with Murder, Criminal Conspiracy, Endangering the Welfare of a Child and related offenses. The two were arrested this past spring for their crimes.