Donald Farrell, 19, died after the assault during an apparent mugging on the Glassboro, New Jersey campus.
Surveillance cameras from a nearby store captured an image of one of the suspects.
But police believe there may have been four or five people involved.
The image, along with the offer of a $100,000 reward for information, continues to air on digital billboards throughout the region.
Anyone with information is asked to contact call authorities at 856-307-7180.
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