They do arrest local people on a regular basis, if you check the county jail web site. Whether or not any of these people have helped with the investigation is unknown. But the way this murder investigation has been conducted is highly unusual, IMO. They imply unflattering things about the victims, instill fear and paranoia in the community and ultimately get them to turn against each other. They've offered no protection to surviving family members who might become targets of the killers. If not for the news media lawsuits, the investigation would be completely silent, on it's way to becoming a cold case.
It's been compared to the investigation into the deaths of Abigail Williams & Liberty German in Delphi, IN where there's a big reward, regular contact with the public and plenty of cooperation with other LE agencies. Very different.
Perhaps putting someone new in charge will help get things back on track.
JMO
ETA: Maybe the best idea is, as the anniversary of this horrible crime approaches, it might be a good idea to get a social media campaign going. Encourage everyone to call Congressman Brad Wenstrup
http://wenstrup.house.gov/, Senator Rob Portman
https://www.congress.gov/member/rob-portman/P000449 and Senator Sherrod Brown
https://www.congress.gov/member/sherrod-brown/B000944.
Members of Congress routinely see and discuss classified information, they would be trustworthy to view all the files on this case and assure the public the investigation is being pursued effectively.
It's a place to start.