A Vancouver Island man has pleaded guilty in what police believe is the largest voyeurism prosecution in Canadian history after investigators uncovered thousands of secretly recorded images and videos involving 652 women and girls.Yin Yeung Derek Chan, 39, of Saanich, entered guilty pleas to multiple offences connected to years of covert recordings made without the knowledge or consent of victims across the Greater Victoria area.The case began in January 2024 after Saanich Police detectives discovered voyeuristic photos and videos being uploaded online through a popular image-sharing social media platform.The investigation, led by the Saanich Police Special Investigation Section with assistance from the B.C. Integrated Child Exploitation Unit, traced the material back to Chan.Police noted Chan was already known to authorities following an earlier voyeurism conviction involving secret recordings of a woman inside a shopping mall change room.Investigators arrested Chan at his Saanich residence on April 11, 2024, where they seized electronic devices containing thousands of images and more than 28 hours of video footage secretly recorded between 2017 and 2023..According to police, the recordings captured women and girls inside businesses, at beaches and, in some cases, through the windows of private homes.Detectives later determined 652 separate victims appeared in the material, though only 40 women and girls have so far been formally identified and contacted by investigators.Police said many of the recordings had been uploaded to websites viewed internationally, prompting formal requests to remove the material from online platforms.Chan was initially released on conditions following his arrest but was taken back into custody on Jan. 30, 2025, where he has remained detained.He pleaded guilty in October 2025 to several offences, including secretly observing and recording individuals where they had a reasonable expectation of privacy, recording for a sexual purpose, making child pornography, publishing illegally obtained recordings and breaching court-ordered conditions linked to his earlier conviction.Some of the identified victims submitted victim impact statements ahead of sentencing.Chan is scheduled to be sentenced Thursday at Victoria Law Courts.Police say efforts remain underway to identify the hundreds of remaining victims.Investigators are asking anyone who believes they may have been targeted to contact Saanich Police by email.Greater Victoria Victim Services has also been assisting victims throughout the investigation and continues offering support to anyone who comes forward.