Can someone explain this verb conjugation?

Question

This is taken from a songs lyrics

罪は忘れさられた

It translates to

The crime was forgotten

So I'd say this is in passive form except what is the さ doing there ?

Shouldn't it be 忘れられた ?

Then why is the さ there?

Answer 1

I reckon that is a compound word, not just a conjugation. It is not 忘れる, but 忘{わす}れ去る{さる}, meaning "to forget completely".