Anthony Diedrick, 39, a computer operator, has pleaded not guilty to strangling the 27-year-old doctor with a vacuum cleaner cable at her home in St John's Wood, north London, on Boxing Day, 1994.
Nigel Sweeney, for the prosecution, told the Old Bailey that there was no dispute about the origin of three pin-head sized blood specks on the dark pink top that the doctor was wearing when she died.
After consulting Mr Diedrick's counsel, Ronald Thwaites QC, Mr Sweeney said it was not challenged that the DNA identified in the blood stains belonged to the defendant.
Mr Diedrick, of Maida Vale, north London, told police that his relationship with Dr Francisco ended six years before her death, the court has been told.
The prosecution alleges that he became obsessed with the doctor, stalked her before her death, and killed her on the day she was due to fly to America.
Dr Ann Priston, a forensic science expert, told the court that although she had seen the three tiny spots of blood when the top was first examined, she had assumed they belonged to the doctor who had bled slightly from her mouth.
The case was reviewed last year and the piece of clothing was re-examined using new DNA profiling techniques, said Dr Priston.
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