now back to "dateline." >>> six days after the murders of mike and sin thee a mcclelland, hundreds ofed casket contained mike's body and cynthia's ashes, together for eternity. their extended family, united in grief, bid them an emotional farewell. >> i carry a lot of things from them with me. they taught me very well. >> they helped a lot of people before they left this world. >> they really did. they made a large impact on a lot of people. >> a beefed-up multi-agency task force vowed to catch whoever killed the mcclellands and mark hasse. investigators had seen that ford crown victoria on video roaming near the mcclelland home and thought it might be a police car. the terrible possibility it might be one of their own had to be ruled in or out immediately. >> we checked with every law enforcement agency in the area and identified where every police car was in the area. and none of them were even close to where this image was captured. >> next, they looked for anyone who for any reason had issues or disputes involving both prosecutors. >> there didn't seem to be anybody in that group