A document signed by his brother, John III of Sweden, and a nobleman, Bengt Bengtsson Gylta (1514–74), gave Eric's guards in his last prison authorization to poison him if anyone tried to release him.
Un document semnat de fratele său Ioan al III-lea al Suediei și de un nobil, Bengt Bengtsson Gylta (1514–74), acorda autoritatea gărzilor lui Eric să-l otrăvească dacă cineva încerca să-l elibereze.