(Portland, OR)  --  Prosecutors say a man has pleaded guilty to first-degree manslaughter in a homicide case that's more than 20 years old.  Forty-seven-year-old Adrian C. Stafford also pleaded guilty to first-degree conspiracy to commit robbery.  Officials tell KOIN-TV that Stafford, 51-year-old Danny Connor, and 53-year-old Vinson White have all pleaded guilty in the 1995 death of Darrin Ezell.  A fourth suspect is awaiting trial.