The actress whose body was found in the home she shared with a CBBC host may have taken the wrong medication before she died, her fiance's mother has said.
Ms Collins had been planning to start her own production company
After Natasha Collins' death in London, her partner Mark Speight was arrested on suspicion of murder and supplying cocaine, which he vehemently denied.
He would never have "harmed Tash", Mr Speight's mother Jacqueline said.
A mix-up with drugs prescribed for a medical condition may have led to the 31-year-old's death, she added.
Talking to reporters outside her home in Wolverhampton, Mrs Speight said the couple had been together "for quite a while".
"As far as I know, everything was OK between them," she said.
Asked for her reaction to the tragedy, she replied: "I'm in absolute shock. I was only with them at Christmas. They both seemed fine and very happy."
She added: "There is no way on earth that Mark would do anything to harm Tash."
Mr Speight is known as one of the faces of BBC children's TV, particularly the SMart programme, which he has presented since 1995.
He had worked with Ms Collins, who was also a model, on children's series See It Saw It.
She was planning to set up her own production company with compensation she received after a car accident seven years ago.
On Friday a statement was issued on behalf of Ms Collins' mother, whose first name was not given.
"We are all absolutely distraught over the death of Natasha," it read. "She was our loving, caring daughter who was always full of life.
"This is a very emotional time for us as a family. We ask simply to be allowed to grieve."
A spokeswoman for Mr Speight said the presenter had found Ms Collins' body in the bathroom of their home in St John's Wood "and immediately called an ambulance and the police".
"Mark was the only other person present in the flat and has therefore been questioned by police as a matter of course.
"He is assisting police with their enquiries and had nothing to do with Natasha's death," she said, before adding: "Mark is absolutely distraught."
A spokesman for the Metropolitan Police said a suspected drug overdose was one line of inquiry which was being considered.
Further details of the circumstances leading up to Ms Collins' death are unlikely to emerge before a post-mortem is conducted, and this is expected to be on Monday.