Sussex Police are still appealing for information following the incident on 21 October.
A teenage girl was walking through Clair Park late in the afternoon, from the Oathall Road direction when a man approached her in a wooded area.
The man was described as being either black or of mixed ethnic background and wearing a black hooded top and black jogging bottoms.
Detective Chief Superintendent Karrie Bohanna said: “This was a highly distressing incident, and the victim is receiving support from our officers.
“We are pursuing a number of lines of enquiry, and since this report was received, officers have been carrying out high visibility patrols in the area.
“But we are appealing for witnesses or anyone in the area at the time who may have seen something suspicious to come forward.
“This also includes anyone with CCTV, doorbell, dashcam or mobile phone footage in the area at the time who has not already reported this to us.
“The victim described that it was still light outside, this incident happened at a time when lots of people may have been in the area, so we are urging people who may have information to come forward.”
Information can be reported to Sussex Police online or by calling 101 and quoting Operation Oakland.
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