According to a story in the Oregonian ( link to www.oregonlive.com), on January 28, police stopped three black youths, asked if they were gang members, searched them, hit the young woman's head against the pavement causing injury, then lied about it in their report. The cops also reportedly had their guns drawn.
Portland police officer Scott Broughton, who hit the young woman's head against the pavement and then put his knee on her head and applied pressure, was investigated for his involvement in the police murder of Kendra James ( http://portland.indymedia.org/en/2004/08/294246.shtml).
One of the youths recorded the audio of the police encounter on a cell phone (good heads-up move), which can be heard at the Oregonian webpage linked above.
On the day after this incident, January 29, police would shoot unarmed black man Aaron Campbell in the back, killing him ( http://portland.indymedia.org/en/2010/02/397042.shtml).