They are investigating a murder, and they believe the victim's remains were dumped somewhere out here.
Cherita Thomas was just 21 years old, and had just gotten engaged when she disappeared. McGregor and David believe Cherita was victim of a race crime --murdered simply because she was black.
"I was a patrolman 20 years ago. I remember when it happened. I remember working some of the small leads on it," Sgt. McGregor tells correspondent Richard Schlesinger.
"It becomes personal. We've become close to the family. We know it's a solvable case. We know we have a good area where our victim is. And going into this, we thought we had somebody that was gonna help us find her."
After trying everything else, the police last year brought in two new investigators with an unbelievable track record: Sandra Anderson, a dog-handler for 17 years, and Eagle, a mixed breed dog with his own type of pedigree.
"My friend can do magic," says Anderson.
Eagle is widely considered one of the best dogs in history at sniffing out human blood and bones. Ten years ago, Anderson rescued Eagle from the pound, and he returned the favor by turning Anderson into a hot commodity in the world of cold cases.
Sandra and Eagle worked about 1,000 cases before coming to Oscoda. Eagle eventually lived up to his reputation. Amazingly, he started finding human bones, where human searchers couldn't, despite 20 years of trying.
"I felt that everything we were doing at that point was coming together, like it should," says McGregor.
Police have a suspect in this case who they believe they can place in these woods at this spot.
The one thing they lack is any physical evidence that Sharita Thomas' body was dumped here. And that's what made Eagle's discoveries so important.
Eagle and Sandra had spent years building their reputations. In 1999, Mevano Kupasa, an immigrant from Tanzania, was found dead and dismembered in rural Wisconsin. Prosecutors credited Eagle and Sandra with sniffing out tiny traces of her blood in her cousin's apartment.
"Inside the bathroom area, inside the bathtub. On the way to the toilet. The toilet we recovered her DNA. The bathroom wall we recovered her DNA," recalls Patricia Barrett, who prosecuted Kupasa's cousin, Peter Kupasa.
There was other evidence against Kupasa, but the star witness for the prosecution was Eagle, who sniffed out even more: traces of blood on a cutting board and on knives from Kupasa's apartment.
Eagle's findings were considered critical clues that Kupasa murdered his cousin, even though scientists at the Wisconsin crime lab could not confirm his findings.
"I believe it [Eagle] detected something of human matter, as opposed to animal matter, that they were unable to recover," says Barrett, who believed so strongly in Eagle's ability that she brought the dog into court to demonstrate how he could find hidden human blood -- all to the dismay of his defense team.
Peter Kupasa was convicted of murdering his cousin. And Eagle and Anderson had chalked up another conviction. They were profiled on TV shows as the team that solved crimes no one else could.
"Eagle and I have been together 10 years, and go all over the world, and the communication is pretty good," says Anderson.
In 2001, they traveled to Panama to help locate mass graves from the regime of former dictator Manuel Noriega.
In Panama, forensic anthropologists Julie and Frank Saul witnessed Eagle's work firsthand.
Compared to other dogs, how good was Eagle? "If a really good cadaver dog is a 10 on a scale of 1 to 10," says Dr. Saul. "Eagle was a 20."
Anderson was so respected she was called in to help train other dogs -- like Zorro, and his handler, Madison, Wis., police officer Bill Murphy.
What did Anderson teach them? "That this search-and-rescue work is about the victim and nothing else. It's about the victim, period," says Murphy.
Sgt. McGregor, who was searching for Cherita Thomas, trusted in Sandra's reputation and Eagle's. That's why he called them to the woods outside Oscoda, Mich.
Eagle began to find more and more bones in streambeds and rotted trees where police had searched for years. But Officer David was watching Sandra closely as Eagle kept finding bones.
"That was the first time I actually saw her hand go up to the back of her pant leg," says David. "And I didn't think anything of it at the time."
But then, Anderson told Mark David that Eagle had found a bone in a small area that David had just finished searching intensely. "And I'm thinking to myself, 'There was nothing there. I was just on my hands and knees and there was no bone in there,'" recalls David. "I'm positive there was no bone there…It bothered me big-time."
The two Oscoda cops told their superiors they were suspicious, and that they believed Anderson was actually planting evidence for Eagle to find. A federal investigation was launched. But this time, the feds were the ones looking for bones, not Eagle.
"I can tell you there was a search done of her car. And I can tell you that, coupled with other evidence we had, led to the federal district attorney telling us that she's to be arrested at the scene," says Sgt. McGregor. "All of a sudden you find out that everything you've been doing is nothing but a hoax."
Anderson was placed in handcuffs and the local police were in shock.
"I feel like I was cheated because everything to the point we got to was done with a lot of hard work, a lot of loyal legitimate police work," says McGregor. "And we bring someone into my circle, and she totally betrayed us."
Anderson isn't talking on-camera. But there are reports that some of the bones she's alleged to have planted in Oscoda have been traced back to a medical center in Louisiana.
It's raised disturbing questions about the cases Anderson helped close, like Peter Kupasa's, the man convicted of murdering his cousin. Kupasa had his lawyers appeal, but his conviction was upheld, based on evidence Eagle did not provide. Barrett remains confident in the jury's verdict, even if she's less confident in Anderson and the dog.
Would she, however, use Anderson and Eagle again in another case? "At this point in time," she says, "Certainly not."
But Anderson and Eagle still have their staunch supporters.
Zorro's handler, police officer Bill Murphy, still considers Anderson the best in the business. Will these charges put a shadow in his mind about Anderson and Eagle? "No," he says.
But Murphy said that before a surprise announcement Wednesday by Sandra Anderson. After insisting that she was innocent, Anderson pled guilty to obstruction of justice and falsifying evidence, including the planting of bones.
Now, defense attorneys for all those other cases in which she and Eagle helped get convictions could rush to challenge the evidence presented by what was once considered a dynamic duo.
Anderson has pled guilty to multiple felonies, and she could face a maximum of 30 years in prison. But she hopes her plea bargain will result in a much shorter sentence. One other note: in the midst of all this, Sandra's dog Eagle, recently died.
Despite the growing controversy, police in Oscoda, Mich., tell us they expect to make an arrest soon in the Cherita Thomas case -- after more than 20 years.