A left-wing protester spitting on a police officer marching in a Blue Lives Matter demonstration in Chicago last week is gaining so much notoriety that the police department is offering a reward for the protester’s arrest.

A video of the incident shows the crazed protester verbally abusing the stone-faced officer marching with hundreds of other officers before spitting at him and walking away. The off-duty officer, meanwhile, turned his head towards the protester and just kept walking. The video has gained more than 827,000 views on Facebook alone as of Sunday evening.

Chicago’s Fraternal Order of Police offered a $1,000 reward Monday to anyone who had information leading to the left-wing protester’s arrest.

The demonstration, known as “Blue Wednesday,” was a way for the city’s Fraternal Order of Police to voice their displeasure with Mayor Rahm Emanuel.

Members say Emanuel “turned his back” on the city’s police officers because the Chicago Police Board ruled that an officer should be “on a no-pay status” for a fatal shooting in 2015 that the board deemed “unjustified.” The Chicago Police Department superintendent, however, ruled that the officer’s actions were justified—but the board did not take into account the police department’s ruling.

President Trump voiced his support for the “Blue Wednesday” demonstrators, saying that Chicago’s police force has the right to protest against Emanuel for not letting them do their jobs: