"They had no earthly idea that they were being recorded," said Chief Lucky Miller, Mannford Police.
Miller says Smith used a web camera for at least a year to record his roommate's three teenaged children showering. Miller says Smith scratched off small portion of the mirror and replaced it with reflective window tint.
Next, the chief says Smith cut a hole in the wall between the bathroom and his bedroom -- then put the camera inside.
"This guy went to great lengths to disguise the camera and great lengths to disguise the power cord, and even the power cord that went to his computer," the chief said.
"Had you looked at the wall on the other side, you'd have no knowledge that there's a camera inside the wall that's being powered by a power supply that's inside the wall," he said.
It wasn't until after Smith moved out, when the former roommate was getting ready to sell his house, that the camera was discovered.
That roommate called police, just 10 minutes after Smith himself alerted detectives.
"He left the camera there thinking it will never be found by anybody, the next people will move in and everything will be fine but he was sadly mistaken," said Mannford Police Chief Lucky Miller.
Court documents state Smith told officers the video equipment was used in paranormal research.
"Ghost hunting, not buying it, that's why we continued with the investigation," Chief Miller said. And as the questioning continued, the chief said the truth came out.
"When he started telling his story, it was more like he was bragging about what he had done and what he had seen, so we allowed him to continue to tell his story."
After moving from Mannford to Bixby, Smith continued to contact the minor victims through text and Facebook - even suggesting that one of the girls should get a job doing online web cam posting, court records state.
Smith was arrested, but Miller fears there could be more victims out there. Police have sent all Smith's electronic devices to the OSBI for analysis but say Smith was a computer programmer and knew how to get rid of the evidence.