Detectives said yesterday they were anxious to speak to anyone who saw 20-year-old Sarah Alesworth shortly before she was found bludgeoned to death at the family home in Northumberland Avenue, Aylesbury, last Wednesday.
Inspector Tony Everett, of Thames Valley police, said the murder weapon had still not been found.
Detectives are waiting to speak to Sarah's father, Dr Patrick Alesworth, 48, who is in prison in St Malo, Brittany. He was arrested in France after arriving on Thursday on a car ferry from Portsmouth. He drove through a checkpoint and is alleged to have threatened a woman motorist at knifepoint in an attempt to hijack her car. His white Volvo was chased for four hours before a police helicopter tracked it to the town of Ploubalay.
The doctor was remanded in custody by a French examining magistrate on Friday on charges of attempted robbery with violence and violence against the police.
British detectives have obtained a warrant for his arrest in connection with the murder. Extradition could take up to a month.
Insp Everett was waiting for clearance from the French authorities yesterday before sending a team of detectives. He said that interviewing Dr Alesworth was not the only line of inquiry being followed and he urgently needed to speak to witnesses who may have seen something on Wednesday between 8.30am and 3.50pm, when Sarah's mother discovered her body.Reuse content