The police usually release the minimum amount of information on an open case. In the case of the woman's death they may have evidence that there was a personal relationship of some kind with the perp and therefore minimal risk to the public at large. 
Re the gang members, it's been a known fact for some time that there is gang( sometimes violent ) activity in Eugene. No city of any size can avoid it. May as well get used to it, it comes with the drugs and the lack of decent employment prospects for some.