Without a confession or previously undisclosed touch DNA I don't see how a conviction is possible on the current charges.

What evidence could there be? Everything would appear to be circumstantial short of maybe shoe size?

Any guesses?

Edit: Fleshing this out a bit more, but here's the best possible case I can come up with:

1. Link the suspect to EAR activity in Contra Costa via DNA
2. Connecting him to EAR activity provides a link between suspect and shoe lace-style ligatures and the Rancho Cordova area at the time of the homicides. EAR was known to be committing crimes in RC in people's yards at night while armed with a firearm.
3. Shoe lace-style ligature is found at Maggiore crime scene; maybe also shoe size from footprints match. The two are murdered by an assailant with a firearm in someone's yard at night.