Thanks to Google, a sex offender was recently arrested after the company tipped off authorities about finding illegal photos of children in his email. Despite the good that came out of it, it raised a number of questions, such as "does Google regularly look into the contents of our email?" A Gmail spokesperson has gotten in touch with AFP to clear the air and revealed that each image that depicts child sexual abuse actually has a unique digital fingerprint, which a special Google technology can detect. While the spokesperson didn't talk about it in detail, that technology might be what the company supposedly developed last year: a system that can trawl the web and email accounts for child sex images. Gmail's rep made clear, however, that Mountain View only uses the system to detect child porn -- it can't actually parse emails that contain details of any other criminal activity, like burglary.