In the United States, a computer technician who worked at a company was accused of spy on webcam with clients on Mac computers. He apparently installed a remote control program (Lase Trojan) and captured photos of the women when they were changing clothes and even in the shower.
To convince them to take the equipment to the bathroom, it displayed a false system alert requesting to fix the camera's internal sensor and suggested leaving it near the steam for a few minutes (You should fix your internal sensor soon. If unsure what to do, try putting your laptop near hot steam for several minutes to clean the sensor).
The investigation began last year when one of the clients saw suspicious messages on his daughter's computer and alerted the police. Potential victims can search for a program called Camcapture in / Library / WebServer / Documents.
More information: Police press release.
A few months ago, he had commented on a similar case, a guy sent a fake video on Facebook to his victims to infect them and thus take control of the machine, then spied on them and extorted them.
For more information on these topics I recommend the site www.sextorsion.es.
See also: Anti-theft software for Android notebooks and mobiles. Trojan vulnerability allows spying on the attacker.