SECURITY camera footage of a brutal police arrest which ended in a Perth engineer being charged for assault has helped clear the man’s name.

The footage shows the moment engineer Brandt Croswell was grabbed by a police officer and pushed to the ground, his head picked up and slammed on the pavement.

Mr Croswell had made a rude hand gesture at the officer prior to the October 2012 arrest outside The Moon and Sixpence venue in Perth.

On Tuesday, Mr Croswell was cleared of the assault charge after three years in a retrial.

The CCTV footage was key evidence.

It also shows Mr Croswell’s girlfriend filming the incident on her mobile phone.

The woman said her phone was then confiscated and the footage deleted.

Nine News reported the magistrate ruled Mr Croswell did headbutt the officer but he had been provoked and he was scared and defenceless.

“It’s just great the truth has finally come out,” Mr Croswell said.