Chief Stamper, who had been set to step down soon, after six years in the job, said he would stay on until March to help investigators establish what went wrong and why.
He hoped his departure would "depoliticise" a wide-ranging investigation into police behaviour during the 135-nation ministerial conference, which collapsed without agreement, partly as a result of the rowdy scenes of demonstrators facing columns of riot police.
WTO delegates, many of whom were trapped in their hotels last Tuesday by rings of chanting protesters, were stung by tear gas as they attempted to continue their negotiations.
They have also accused police and the Seattle authorities of effectively sabotaging their event by failing to keep the demonstrators at a safe distance from the building.
Civil liberties groups and residents' associations have accused the police of violating the constitution when they set up a so-called "no protest" zone around the meeting and arrested hundreds of peaceful protesters. They have also accused the police of excessive force in their use of tear gas, pepper spray, water cannon and rubber bullets in their efforts to clear the streets.
Seattle's mayor, Paul Schell, who also faces investigation for his role in the debacle, praised the Chief Stamper as a man "of absolute integrity". But that praise was not enough.Reuse content