Trevor Harwell, 20-years-old from Southern California, is accused of using an elaborate trick to snap photographs of naked women in their own bathrooms.

Harwell allegedly installed a malicious software on women’s laptops that would send error pop-up messages urging the women to fix internal sensors by putting their laptop near hot steam for several minutes.

What many of the women did was take their laptops with them to the bathroom before they would shower.  Harwell then took control of the laptops’ webcams and snapped videos and pictures of the naked and undressing women.

He stored the pictures and videos on a remote server and then downloaded them to his own computer.

When police arrested Harwell and took possession of his laptop, they found “hundreds of thousands of still images and videos,” including “many of women undressing or changing clothes,” reported AP.

It’s unclear how Harwell installed the malicious software on his victims’ laptops.  UK’s The Register said he installed it on computers he was given to fix in his job as a computer repairman. However, Harwell's employer said Harwell didn’t do that on the job to the best of their knowledge.

Another theory, offered by investigators, was that he “exploited computers connected to Biola University's internal network,” reported AP.  Many of Harwell’s victims and Harwell himself attended the university.