Police are preparing for protesters during the Republican National Convention, but an area private eye says everyone needs to know the potential danger of one group. 

The hacker group “Anonymous” released a YouTube video calling for action during the RNC and warning people not to listen to Sarasota private investigator Bill Warner.

The video mentions Tampa Police Chief Jane Castor, as well as Warner.

“This is pretty bad," Warner said. "There's a lot of trouble coming our way.”

He said he knows the group has been tracking him for a while, primarily because he has spent the last six months tracking it.

From the cyber world to the real world, graffiti of the image used in the video was found Tuesday on a downtown Tampa building on Florida Avenue. 

Tampa police say pipes and bricks were also found near the graphic. Tampa police said they are working to see if the two are connected, but Warner is already convinced.

“I think it was an accident," he said. "I think the mural they put up on the wall, the graffiti mural, it was pretty well done. 

"I think the person who did it may have been played by the Occupy Movement and the Black Bloc people. He tagged it with his name. You wouldn't do that with the poles right there.

"I think they came back possibly later and put the bricks and poles up there. They used that as a signature to where the bricks and the poles were going to be."

Warner wants the public to know what he says the group is capable of. He said they are organized and scenes like the ones shown in the YouTube clip should not be taken lightly.

"Have they more locations with those bricks on roofs some place around town?" Warner said. "I don't know, but they've done it already. They've done surveillance around the area. They know where to go. This is right across the street from the hotel where the media is going to stay."

The video has hundreds of hits. Warner said members of the group historically wear all black. He warns people going to the RNC to keep their eyes open and be prepared. Warner said he believes law enforcement is prepared for all types of protesters.