Two artists said they were in "disbelief" after an investigation into damage caused to their gallery was dropped by police.
The Market Gallery had been due to open in a former Wilko store in South Shields when it was broken into and vandalised and videos of trespassers in the building were posted online.
Laura Robertson and Theodore Godfrey-Cass said since being told Northumbria Police had dropped the case, the building had been graffitied again and they had been harassed by those they believe are responsible.
The Northumbria force said the case had been dropped due to "evidential difficulties" but inquiries into criminal damage outside the premises were ongoing.