Oscoda, Mich. ? After two frustrating decades, police thought they were about to crack the case of a missing black woman believed to have been murdered in a racially motivated attack.

One reason for their optimism was Sandra Anderson, celebrated trainer and handler of cadaver-sniffing dogs. She had agreed to join the search of a forest and bring along Eagle, a canine with a reputation as a whiz at finding human remains.

But Anderson and Eagle found no sign of the missing woman, Cherita Thomas. Instead, during her third and final visit to the woods, Anderson herself was taken away in handcuffs, accused of planting bones at the scene.

A federal grand jury in Detroit indicted her Aug. 20 on 10 counts of evidence tampering, obstruction of justice and lying to investigators. She could get up to 65 years in prison if convicted.

The indictment contends Anderson faked evidence in several cases in Michigan and Ohio. Not only did she plant bones in search areas, it says, but she also used her own body fluids to stain a saw blade, coins and a piece of cloth.

Anderson, who did not return calls for comment, claims to have conducted about 200 searches annually for law enforcement and historical preservation groups over 17 years. Dawn Clenney, FBI agent in Detroit, would not speculate on how many cases Anderson’s alleged actions might have tainted.

Even if she is found guilty, it does not necessarily mean every defendant she helped put behind bars will go free.

“There’s going to be a question of whether the fraud was decisive in reaching the conviction,” said Richard Friedman, a University of Michigan law professor. “If courts are confident the evidence against the defendant was overwhelming, they’re unlikely to throw the conviction out.”

Anderson, 43, of Midland, Mich., is a legend among trainers and handlers of cadaver dogs — “the best of the best,” said Adela Morris, founder of the Institute for Canine Research near San Francisco.

Sandra Anderson, trainer and handler of cadaver-sniffing dogs, coaxes Eagle before a simulated evidence search for the media. A federal grand jury in Detroit indicted Anderson in August 2003, on 10 counts of evidence tampering, obstruction of justice and lying to investigators.

She was invited to Panama and Bosnia to look for victims of political repression, and to ground zero in New York after the terrorist attacks. They were featured on TV’s “Unsolved Mysteries” after helping convict a Michigan biochemist of dismembering his wife.