Authorities said that, in January, two separate vandalism incidents took place at the Islamic Center of Charleston.
The words "utterly blessed" and an unknown symbol were spray-painted on the mosque.
In February, police released surveillance pictures of three people who may be connected to the incidents.
The Council on American-Islamic Relations previously called for police to consider the possibility of anti-Islamic bias as a motive for the crimes. At the time, a department spokesman said officers were continuing to investigate the incidents as vandalism, but that they were not ruling anything out.
On Monday, we told you about a man who volunteered to clean graffiti off the property. That same night, we asked authorities if any suspects had been identified.