Rodas was found deceased shortly after 7:30 a.m. Thursday near 33153 Mulholland Highway north of Malibu, according to the Los Angeles County Sheriff's Department.
On Tuesday, the sheriff's department said an autopsy was conducted on Dec. 2.
"The Medical Examiner-Coroner Office did not find any obvious signs of trauma and preliminary findings indicated there were narcotics in the decedent's body," the department wrote.
"At this time, the Los Angeles County Sheriff's Homicide Investigators are treating this incident as a possible narcotics overdose."
The department did not specify the type of narcotic suspected. The investigation is continuing.
Prior to the new report, her family was raising questions about her death based on the circumstances of her disappearance and her recent transition, which they feared could subject her to hate.
Friends who spoke with Eyewitness News on Monday said Rodas had just recently transitioned.
"You could feel that that she was, like, really happy to finally be out of her shell and be who she really wanted to be," said Nicolette Esquivel. "It was really nice to see her flourish."
Rodas' family said her phone was found at another Malibu location and her car was found in downtown Los Angeles.
"To go from downtown L.A., drive her all the way to the middle of nowhere Malibu, that does not sound right," said Esquivel.
They said Rodas recently encountered hate and they feared she was targeted for violence because she's a transgender woman.
Rodas played the guitar and was a part of a popular San Fernando Valley band. She was proud to share the story of her transition, her friends say.
A GoFundMe has been created to help Rodas' family.
The video in the media player above is from an earlier report on this story.