Willie Spies said he would be going to the High Court in Pretoria on an urgent basis this evening to have O'Sullivan released immediately.
"He has been arrested in front of my offices this afternoon after a consultation‚" Spies said.
He said there were "seven different police cars" involved in the arrest.
Spies believes that police "interjected communication" between himself and O'Sullivan.
"This is in contravention of a High Court order from November 2016. I showed this order to Brigadier Ncube (the arresting offcer) and he was of the view that it related to another matter‚" Spies said.
- READ MORE: Paul O'Sullivan arrested - reportsSeveral reports are quoting forensic investigator Paul O’ Sullivan’s lawyer Willie Spies as confirming that he has been arrested.
He added that the acting police commissioner‚ Khomotso Phahlane‚ had agreed that O'Sullivan would be given 48 hours’ notice if he was due to be arrested.
The order allowed for the investigator to hand himself over to a police station‚ Spies said‚ an agreement that police had not stuck to.
Spies said O'Sullivan has been charged with impersonating an Independent Police Investigative Directorate officer‚ and a similar charge has been leveled against one of O'Sullivan's associates‚ attorney Sarah Trent.
Trent was arrested on Friday and released at the weekend.
O'Sullivan has been assisting the directorate in investigating Phahlane for corruption.
Meanwhile police refused to confirm the arrest.
"I'm not in a position to call or confirm. Our policy is not to identify an arrested person until they have appeared in court; if there is any change I will advise you‚" said police spokesman Brigadier Sally de Beer.
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