With the cooperation of Google, police in Houston, Texas, arrested a 41-year-old man for possession of child pornography.

John Henry Skillern, by day a cook at Denny's, in his spare time a registered sex offender, used his Gmail account to send three illicit photos of a female child.

Google's automatic scanning software includes the ability to detect photographs of this nature. How that works, exactly, Google is not saying, since the company doesn't want to give away its secrets while possibly helping other sex offenders learn how to duck the software.

Google then tipped off the National Center for Missing and Exploited Children to the email and picture. Armed with the evidence, Houston police arrested Skillern.

"He was trying to get around getting caught, he was trying to keep it inside his email," said Detective David Nettles of the Houston Metro Internet Crimes Against Children Task Force. "I can't see that information, I can't see that photo, but Google can."

Police obtained a search warrant and found other child pornography samples on Skillern's tablet and phone. Texts and emails in which Skillern discussed his interest in children were also discovered.

Videos of young children visiting the restaurant where Skillern worked were also found on his phone.

It is fairly common knowledge that Google uses software that scans the content of Gmail messages for keywords that can be used to direct more targeted ads and search results. Although Google advises users that the company has the right to do this, as noted in its terms of service that users must consent to at sign-up, the company updated its terms of service in April in the aftermath of a court case in March that questioned Google's practices.

The updated policy now reads, "Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection. This analysis occurs as the content is sent, received and when it is stored."

The use of Google's scanning software to detect child pornography is, on the surface, a good thing. It does raise serious concerns about how this technology can be misused, either through malicious intent or through mistaken analysis, to infringe on the privacy and legal rights of law-abiding citizens and businesses. One of many technology issues that will need to be more closely, and wisely, adjudicated.

Skillern, who was convicted in 1994 of sexually assaulting an eight-year-old boy, has been charged with possession of child pornography and with promotion of same. His bond has been set at $200,000.