Innocent people have been branded as child abusers after malware infected their PCs, an AP investigation has discovered.

Technically sophisticated abusers sometimes store images of child abuse on PCs infected by Trojans that grant them illicit access to compromised machines.

The plight of those framed in this way is all the worse because paedophiles commonly use supposed malware infections of their PCs to explain the presence of images of child abuse. Because of this the “Trojan did it” defence is understandably met with scepticism from law enforcement professionals.

“It’s an example of the old `dog ate my homework’ excuse,” says Phil Malone, director of the Cyberlaw Clinic at Harvard’s Berkman Center for Internet & Society told AP. “The problem is, sometimes the dog does eat your homework.”

Register: How malware frames the innocent for child abuse