A couple found dead in a Frankley maisonette by their young daughter died of an accidental overdose of a Class A drug.
The bodies of Suzanne Van Hagen, 34, and boyfriend John Worton, 37, were discovered in the bedroom of their home in Miranda Close on February 8.
Ms Van Hagen's nine-year-old daughter, who was in the property at the time, made the grim discovery and raised the alarm.
The first post mortem proved inconclusive, but further toxicology reports have shown the couple died of what is believed to be an accidental overdose of a Class A amphetamine.
The case will now be passed to the coroner and an inquest will be opened and adjourned in the next few weeks.
The schoolgirl dialled 999 after finding the bodies of her mum and step-dad and she is now being cared for by her grandparents.
Police said Ms Van Hagen's body was found in bed, while her boyfriend was discovered on the sofa. Neither had any obvious signs of trauma or injuries.
Ms Van Hagen, who is thought to have worked as a nurse, was a former pupil at Birmingham's top Catholic girls' school, St Paul's, in Edgbaston.
The headmistress, Dawn Casserly, previously paid tribute to her.
"Suzanne was a charming and delightful young lady. She enriched our school community in her quality of person and was an exemplary pupil," she said.
"We remember her extremely fondly and have prayed for her and her family in their great loss."
Neighbours told how the couple had lived at the property for about a year and claimed Mr Worton had been released from the nearby Reaside psychiatric unit at Christmas after being there for two and a half years.
They said the couple had been together for about five years and Ms Van Hagen was "very friendly and really nice" and Mr Worton brought up her daughter as if she was his own and doted on her.
A spokeswoman for Birmingham and Solihull Mental Health NHS Foundation Trust, which runs Reaside, refused to comment on whether Mr Worton had ever been a patient.