(CNN) -- University of Delaware students are being offered counseling after a doctoral student allegedly hid video cameras in restrooms around the university's Newark campus over a two-year period.
Police were alerted after a hidden camera was discovered in a women's restroom on June 27, the university said.
An investigation led to the arrest of 38-year-old Javier Mendiola-Soto, a doctoral student from Mexico. Mendiola-Soto has been charged with 21 counts of violation of privacy. His visa has been revoked, and he is in custody.
Police searching Mendiola-Soto's home found approximately 1,500 computer video files.
"The analysis concluded that the suspect hid video cameras in other restrooms both on and off campus over a more than two-year period from 2012 until his arrest this month," the university said in a statement.
"The scope of the recordings continues to be a focus of the investigation, and the police are attempting conclusively to identify all potential recorded locations."
Recordings have been traced to two restrooms at the Delaware Biotechnology Institute -- where Mendiola-Soto worked -- a unisex bathroom in the building housing the education department, and women's restrooms in a library, memorial hall and laboratory, the university said.
The investigation has so far identified approximately 40 potential victims. Police are contacting victims, and the university is offering counseling to anyone who requests it in connection with the case.
"It is extremely disturbing that this crime was perpetrated against our community invading the privacy of so many women on and around this campus," university President Patrick Harker said.
"We have implemented several actions already, including security sweeps of all restrooms and changing rooms on all campuses, randomly timed examinations of all restrooms by custodial staff and increased police patrols throughout buildings," he said.
The university's head of campus and public safety, Skip Homiak, said new technology had increased the risk of such crimes.
"Invasions of privacy crimes are becoming an increasing concern on college campuses and in public areas given the ready access to small and sophisticated spying devices," he said.
The university said the investigation was being conducted "under strict guidelines and protocols designed to protect the privacy of any individual whose image may have been captured on video." The video evidence is being securely stored and will be destroyed after criminal proceedings end, it said.
Police say they don't think the images have been uploaded to the Internet or shared.
People who think they may have been recorded should contact the University Police Department hotline at 302-831-4800.