The Crown Prosecution Service has been fined £200,000 after laptops containing videos of police interviews with sex assault victims, including evidence which is believed to be linked to Jimmy Savile's former chauffeur, were stolen.
The CPS lost interviews linked to 31 investigations, including some with victims of sex and violence offences.
The Information Commissioner's Office (ICO) said one of the cases related to historical allegations against "a high-profile individual" - thought to refer to Savile's former chauffeur Ray Teret, who was jailed last year for sex offences.
The two laptops, which contained interviews with 43 victims and witnesses, were stolen last year.
The videos were being edited by a Manchester-based film company so that they could be used in criminal proceedings when they were stolen from a flat used by the film company as a studio.
The laptops, which were left on a desk, were password protected but not encrypted and the studio had no alarm and insufficient security, the ICO said.
The ICO said many of the victims were vulnerable and had already endured distressing interviews with police.
In the videos, they talked openly and referred to the names of the offenders.
The police recovered the laptops eight days later and caught the burglar. The ICO said as far as it was aware, they had not been accessed by anyone else.
But the watchdog ruled that the CPS was negligent when it failed to ensure the videos were kept safe and "did not take into account the substantial distress that would be caused if the videos were lost".
The Press Association reported that ICO Head of Enforcement Stephen Eckersley, said: "Handling videos of police interviews containing highly sensitive personal data is central to what the CPS does.
"The CPS was aware of the graphic and distressing nature of the personal data contained in the videos, but was complacent in protecting that information.
"The consequences of failing to keep that data safe should have been obvious to them."
Eckersley added: "If this information had been misused or disclosed to others then the consequences could have resulted in acts of reprisal."
The CPS reported the incident to the ICO and informed the victims and witnesses involved. The ICO received complaints from three affected people.
As part its investigation, the ICO learned that the CPS had been using the same film company since 2002.
Unencrypted DVDs were delivered to the studios using a national courier firm although in urgent cases, the film editor would collect the DVDs from the CPS in person and take them to the studio using public transport.
The ICO found that this constituted an ongoing contravention of the Data Protection Act.