“I gave my PC to a repair shop. On it, he thought he saw child porn (He was wrong) so he took it to police office. Did he stay in legal bounds? I didn’t give permission.”

In many, if not most, states such employees are bound by state law to report anything that they believe indicates child abuse, including child pornography. You may find this article of some interest, and instructive:

Computer Technician Busts Child Porn Enthusiast Employer