I think that OROCHIMARU when he was a member of akatsuki resurected The 4th hokage in order to controll the organisation and becoming the Boss.
RESURECTING NO JUTSU
with that jutsu he resurected the 1st and 2nd hokage in the battle with SARUTOBI-SAMA
but the 4th was very stong to get controlled by Orochimaru
and became the boss of akatsuki