King County prosecutors have decided not to charge Zachary Treisman, one of two cyclists arrested during last week's Critical Mass demonstration in downtown Seattle, with assaulting a police officer — for now.

Dan Donohoe, spokesman for King County Prosecuting Attorney Norm Maleng, said that prosecutors need more time to review the case before making a final charging decision. He estimated that could take anywhere from several days to a few weeks.

Treisman and cyclist Jason Brien were arrested by plainclothes King County sheriff's detectives Friday during a monthly Critical Mass demonstration for bicyclist awareness, after Brien blocked an intersection. Demonstrators and other witnesses have complained that the detectives didn't immediately identify themselves as police and used excessive force.

The sheriff's office has responded that detectives identified themselves before making any arrests, and that Treisman put one of the detectives in a "choke-hold" during the fracas.

Thursday, Treisman returned to the King County Jail, where he spent the night last Friday, to hear the prosecutors' decision. A few dozen of his backers gathered outside to show their support.

"Mr. Treisman was basically a victim in this case," said his attorney, David Speikers.

Speikers complained that the sheriff's office won't look at evidence he has offered them, including several statements from Critical Mass participants that concur with Treisman's account.

The sheriff's office did not return repeated phone messages Thursday.

Seattle Times staff reporter Sara Jean Green contributed to this report.

Joe Mullin: 206-464-2761 or jmullin@seattletimes.com