Accused of assaulting a prisoner, the trial for a special constable at the London courthouse continued on Friday.

Const. Craig Pickering allegedly assaulted Timothy Van Dusen last May.

Surveillance video of the holding cells under the courthouse show Van Dusen being directed to the dry cells - specials cells with nothing but a drain.

On the stand, London police Sgt. David Ellyatt explained they are used for, "Any person who is acting out, or difficult to manage and control safely."

Van Dusen is currently serving a sentence for uttering threats to an officer. In March, he was convicted of assaulting an officer.

But last May when the assault allegedly took place, he was making a court appearance on a mischief charge because two weeks earlier he set off the court's fire sprinklers, something he threatened to do again on that day.

You can see the officers, including Pickering, putting handcuffs and shackles on the prisoner to prevent that from happening.

Special Const. Damian Gorka testified "[Van Dusen] was saying, 'Do whatever you want, I'm still going to set off the sprinkler...Van Dusen tried to grab [Pickering], there was some resistance."

On the stand Special Const. Scott Ashley added, "Mr. Van Dusen was very obnoxious, verbally abusive, he wasn't compliant. It didn't go smoothly"

The video shows Pickering forcing Van Dusen into the cell, then Van Dusen on the floor, mouth apparently bloodied from hitting the wall.

Van Dusen told the court, "If I was trying to resist, I would've tried to break my fall so I didn't break my teeth...I don't give a crap if he's found guilty or not guilty."

Pickering's defence is expected to hinge on Section 25 of the Criminal Code, that as a peace officer he acted on reasonable grounds to do his job and used the correct amount of force.

Van Dusen settled a lawsuit against the London Police Service for an undiscolsed sum Friday.

Pickering takes the stand in his own defence on May 7.