Pennsylvania authorities arrested three senior citizens and another suspect today for allegedly orchestrating a million-dollar drug trade in the state.Richard David Sallade, 71; Patricia Ann Quinn, 67; Craig William Pfister, 50; and Bruce Alan Johnson, 67, were accused of trafficking synthetic marijuana , and authorities say they seized $1.6 million worth -- more than 360 pounds -- when arresting the group."This is kind of an unusual case," said Pennsylvania Attorney General spokesman Jeffrey Johnson, referring to the ages of the accused.Senior citizens are not commonly involved in criminal activity: the Bureau of Justice Statistics reported in September that 10 percent of America's prison population was 55 or older, and only two percent was 65 or older.Sallade allegedly received multiple packages of synthetic drugs at his business in Cranberry Township, with shipments coming from New York and Massachusetts, according to prosecutors.The group would sell the drugs from tobacco and drug-paraphernalia shops operated by Sallade and Quinn, and customers came from Pennsylvania, Ohio, and West Virginia, prosecutors allege.Bail was set at $50,000 each for Sallade and Quinn, and $10,000 apiece for Pfister and Johnson.All four were released on bail and are expected to stand trial at a later date.