A witness in the shooting death of off-duty Mount Vernon Officer Christopher Ridley went public Wednesday.

Efrem Burgos, 51, claims he saw Westchester County Police Officer Frank Oliveri shoot Ridley in the head point-blank during a friendly fire incident in 2007.

"Officer Ridley was falling back with his hands open, but still holding his gun for dear life," says Burgos. "As he was falling down ? Officer Oliveri came from behind the tree - he was using it for cover at that time - and [shot Ridley] right in his head."

Oliveri and three other officers were later cleared of any wrongdoing by a grand jury, but Ridley's father disputes the decision and has brought a $90 million wrongful death lawsuit against the county.

Burgos is also suing Westchester County, claiming officers harassed and arrested him numerous times after the incident to keep him quiet.

To watch the full news conference with eyewitnesses of the friendly fire police shooting of Christopher Ridley, go to channel 612 on your iO digital cable box and select iO Extra.