Before this study, the sources of the pollution were never satisfactorily explained, said Wotawa.

CNN: Canadian forest fires add to U.S. pollution

Father Dimitry himself never satisfactorily explained his recantation, though it ended his mission as a dissident priest.

ECONOMIST: Obituary: Dimitry Dudko | The

London (CNN) -- A British spy found dead at his home in 2010 -- his naked body padlocked inside a large red carrying bag stowed in the bathtub -- was either suffocated or poisoned, but it is unlikely his death will ever be satisfactorily explained, coroner Fiona Wilcox said Wednesday.

CNN: STORY HIGHLIGHTS