morphemes for 'returned'

[lineker1976]

returned = {return} + {-ed} = 2 morphemes

or is it {re} + {turn} + {-ed} = 3 morphemes

which one is correct?

[sash2008]

returned = {return} + {-ed} = 2 morphemes

or is it {re} + {turn} + {-ed} = 3 morphemes

which one is correct?

The second one is correct.
re-turn-ed
3 morphemes.
The root is turn
plus the prefix "re" which is a derivational morpheme
plus the suffix "ed" which is a grammatical and inflectional morpheme.