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.
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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.