The past of Yamask

When we look at the Pokédex entry of Yamask, we read: 

Black Edition: "Each of them carries a mask that used to be its face when it was human. Sometimes they look at it and cry."

Yamask's Pokédex entry

White Edition: "These Pokémon arose from the spirits of people interred in graves in past ages. Each retains memories of its former life."

So...we catch dead people's spirits? And if you look at the mask you can see its human face?

That makes me imagine...would it be possible to catch your deceased relatives?