On 6 June 1991 the mother and businesswoman was stabbed more than 50 times in a car park of a leisure centre in west London – yet no one ever reported seeing the attack or killer's escape. Could a new forensic review lead detectives to the culprit?

On the Sky News Daily podcast, Jonathan Samuels is joined by Penny's daughter Lauren Bell, plus criminology lecturer Kirsty Bennett tells us how many such cases go unsolved in England and Wales.

Daily podcast team:
Podcast producer - Annie Joyce
Podcast producer - Nicola Eyers
Podcast producer - Lauren Pinkney
Interviews producer - Tatiana Alderson
Archive - Simon Windsor
Archive - Rob Fellowes
Archive - Nelly Stefanova
Music - Steven Wheeler