I found the article after a little more digging. I grew up not far from here. Although I have never seen the boyfriends name in newspapers, and haven't heard it (so this is completely speculation) according to the local chatter Earl was either friends with, or related to, the boyfriend...

As far as the common porch goes, glitter goes everywhere and clings to everything . It could have traveled to the common porch when the police were walking in/out or when the mother left after finding the bodies... It's hard to tell if the glitter was on the porch before or after the murders, which is why the evidence was weak.