The medical examiner in New Jersey's Camden County says twin 7-month-old sisters found unresponsive in their cribs died of natural causes.
The county prosecutor's office on Friday did not say how Jessenia and Juliana Rodriguez-Garnett died.
"At this time, my office will not be releasing the cause of death out of respect for the deceased," Camden County Prosecutor Mary Colalillo said.
The girls' mother, Alexandria Garnett, found them in their crib in their Lindenwold apartment on March 22.
She could be heard screaming on a 911 call that they "are not breathing and both are purple."
A dispatcher told her how to perform CPR on the children, and she tried to revive them, but they remained unresponsive. Police arrived moments later, and the roughly six-minute call soon ended.
The sisters' funeral will take place at Wooster Funeral Home in Clementon on Saturday.