An adviser to Mayor Bill de Blasio on behavioral health says he was arrested while videotaping police's encounter with another person who has mental illness, and he wasn't the only one. NY1's Dean Meminger has the exclusive details.

Five Mualimm-Ak, a member of Mayor Bill de Blasio's behavioral health task force, says he was roughed up by police and arrested.

"This other officer came out, whipped out the baton, hit, kicked, assaulted us," Mualimm-Ak says.

Joseph "Jazz" Hayden of the anti-police brutality group All Things Harlem says he was trying to videotape the police's encounter with an emotionally disturbed man on 57th Street Tuesday night when the handcuffs were slapped on him and Mualimm-Ak.

"We are not interfering. We are here just to watch you provide courtesy, professionalism and respect, as you have on your car," Hayden said.

The two men appeared in court Wednesday on charges that they obstructed the police from doing their jobs and resisted arrest, among other things.  

The NYPD says as they were dealing with a mentally ill man, the pair made him lose control and bang his head against a wall.

Hayden has been documenting police interactions for years with All Things Harlem.

Jazz and Five and some of the others who were there on 57th Street say initially, police were being polite, but one officer made the situation chaotic.

"He's about 6-foot-2, maybe 250 pounds, and he keeps pushing me back," Hayden said. "I've never run into a policeman like this. This guy was totally out of control, man. He was totally out of control."

Their lawyers say they are continuing to study all of the cellphone video. Police want to look at it as well.

Mualimm-Ak has spoken to the mayor and City Council about mental health and incarceration. He says he's outraged by this incident.

"I will be taking up with the mayor and the task force later on because those procedures are not still being met," he said.

"The administration is committed to increasing police transparency while ensuring our hardworking officers can effectively perform their duties," the mayor's office said in a statement that it sent to NY1.