A former US official has admitted stalking women and extorting sexually explicit material from them after hacking into their emails.
Michael Ford, who worked in the American embassy in London, pleaded guilty to nine charges of cyber-stalking, seven of computer hacking to extort and one of wire fraud.
He preyed on sorority members at US universities and aspiring models.
Ford used the details he learned after hacking the women to find new victims.
The 36-year-old, from Atlanta, in the American state of Georgia, posed as technical support staff from a well-known email company and sent phishing messages to thousands of potential victims.
Pretending to be a member of the non-existent account-deletion team, he told them their accounts would be closed unless they sent him their passwords.
He then accessed their email and social media accounts in search of explicit photos and other personal information, such as home and work addresses, employment information and details about family members.
He used that information to demand additional sexually explicit material, such as videos of the women undressing in changing rooms at pools and shops.
If they refused, Ford would respond with escalating threats that included messages such as: "Don't worry, it's not like I know where you live."
He also posted explicit photos of the women online or sent them to friends and family.
Between January 2013 and May 2015, while employed at the embassy, he hacked into more than 400 online accounts belonging to at least 200 victims and forwarded at least 1,300 messages to himself from those accounts.
Arrested in May at Atlanta's airport, preparing to board a flight to London, he was charged in August and had initially pleaded not guilty in September.
He will be sentenced on 16 February 2016.
The cyber-stalking and hacking charges each carry a maximum of five years in prison, while the wire fraud charge carries up to 20 years in prison.
Each of the 17 charges is punishable by a fine of up to $250,000 (£165,000).