Hundreds of indecent images of children have been found on the computer of a deputy head teacher who was recently found dead.
Martin Goldberg, 46, a maths teacher at Thorpe Hall School, in Southend, committed suicide at his home in Shoeburyness on 10 September. Police said they are not looking for anyone in connection with his death.
Goldberg was found dead a day after policed questioned him on allegations he bought explicit images of boys online. He was not arrested at the time due to insufficient evidence.
Essex Police continued their investigation into Goldberg and discovered hundreds of images on his computer and other media devices found at his home.
Officers said they have recovered images that appear to have come from a camera hidden inside a bag.
Police said this hidden camera was used to film boys undressing in the school's male changing rooms, in the changing rooms at Southend Leisure and Tennis Centre swimming pool in Southend and two other unidentified locations.
In total there are 75 indecent images from Thorpe Hall School changing rooms, 465 taken from the swimming pool and 38 from the other two locations.
Detectives said four children from Goldberg's photos have been identified and their parents informed. Many of the children cannot be identified as their faces are obscured or the quality of the images too poor.
Police believe the images were taken from 2000 onwards and the boys appear to be aged between nine and 12. Police said there is no evidence Goldberg made any inappropriate physical contact with the children or that he shared the images with anyone else.
Thorpe Hall School have been co-operating with police and said there have found no evidence to suggest that anyone else was involved in Goldberg's criminal activity.
Essex Police said they understand the news may be "extremely distressing" to both parents and children and has set up a special number for people to call if they have any concerns.
A spokesperson added: "Thorpe Hall School has also put in place measures to provide support to its pupils.
"It is also important to remember that Martin Goldberg's family are still coming to terms with both his death and his offending and Essex Police would request that they should be given the necessary privacy to do so.
"The priority for the police now is to support those affected and we are continuing to work with the school, Southend Borough Council, Essex County Council and others to provide that support and ensure that all appropriate action is taken."
Andrew Hampton, headteacher at Thorpe Hall School, said everyone at the school feels "angry and betrayed" at Goldberg's actions.
He added: "The school governors and staff are all very shocked by the news about Mr Goldberg. He was a well-regarded teacher who had an exemplary record during his 23 years at the school and there were no indications whatsoever that Mr Goldberg was leading a double life.
"Everyone at Thorpe Hall School feels surprised, angry and betrayed. Our immediate focus is on supporting our pupils, parents and staff at this difficult time.
"An incident such as this is very alarming and no one could have foreseen it. Our aim now is to move forward, with the safeguarding of our pupils and the quality of their education remaining our very highest priority."
Those with concerns about Goldberg can call 0800 056 0944, or +44 207 158 0010 if they are outside of the UK.