The man, who is described as being in his twenties or thirties, slim, with dark short hair and of Asian appearance, was seen entering the grounds of Ifield Community College through a gap in the fence at about 7pm on Wednesday, 5 May.
He then committed an indecent act. Sussex Police say he was also seen in the same location the following Sunday and officers would like to speak to anyone who can help to identify him.
PC Clare Diamond said; “If you can help us identify this man please contact us either online or by calling 101, quoting serial 1307 of 05/05.”
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