Tutti is a Cadaver Dog used by the FBI and Forensic teams to identify the location of buried human remains. When Tutti finds human remains; he indicates this by lying down. Brennan and Tutti's trainer, Maggie MacGregor, both believe that he is the best Cadaver Dog in the world.
Brennan: He can. Once I saw Tootie find a dead body wrapped in plastic under concrete, after four years.
Maggie: Tootie can smell decaying blood on a tooth six feet underground.-- The Man in the Wall
Tutti first appeared in The Man in the Wall helping Booth and Brennan search for the remains of Eve Warren in Rulz's Studio which were buried by Randall Hall. At first, Booth doesn't believe that he can find the remains and passed off him lying down as being lazy, but they were able to find the remains they were looking for beneath the floor, wavering his disbelief of his talents.
Tutti appeared again in The Body in the Bounty looking for the rest of the remains of Ray Kaminski in the woods of Western Virginia, which was used as a safehouse for Charles Braverman. Booth again believes that Tutti wouldn't be able to find the remains, stating that he got smart and decided to stay away from human remains altogether, but Tutti was able to find the remains, proving Booth wrong again.