Is there reason to suspect a second person could be involved? I don't see it yet.
They way I assume this happened - JC dumped the body parts in multiple bins that were at the curb last Friday night around the central district (hopefully no more than these two locations) that had been set out for Friday pickup but not yet pulled back in. On Saturday, homeowner #1 noticed the bags in his bin as he pulled the bin back to his house, and homeowner #2 did not. Homeowner #2 has likely placed additional trash bags in his bin this week, then took bin to the curb Friday morning where a trash collector noticed the smell upon lifting the lid.
I personally don't think LE searched all bins in the area this past week, for a few reasons. One is that I've been close to a SPD homicide investigation before and things happened quite... slowly, and that was without a suspect in mind or in custody (ie there was even more need for quick action).
They could go door to door and ask permission from homeowners, but some homeowners wouldn't be home.
Had LE gotten search warrants for every property in the whole neighborhood, I think media would have known about it. And they don't grant search warrants for blanket searches, no just cause.
SPD would not approach bins on private property without permission.
I think a more likely scenario is they were working with Seattle Public Utilities to have sanitation workers look through every bin during routine pickups this week. Perhaps they even has LE along with them (though that is doubtful, I read that SPD is short about 200 officers in order to be able to meet 911 demand).
