Lincoln Younes, who plays the Summer Bay student, recently teased that Casey has been hiding something "disturbing" that he did during his time in juvenile detention.
Fans in Australia have now seen Casey confess all after his friend Tyler, who witnessed the incident, threatened to tell Brax and Heath the truth.
In a heart-to-heart with schoolteacher Henri (Emma Leonard), Casey admitted that he lost control while trying to protect Tyler from someone who had been victimising him in juvie.
When the bully pulled a knife against Tyler during kitchen duty one day, Casey stepped in by grabbing some hot oil from the stove and throwing it at him.
Casey is now guilt-ridden as the teen in question is scarred for life because of him.
The young River Boy also has more troubles ahead as he will have a terrifying showdown with Tyler in an upcoming episode.
Home and Away fans in the UK can see Casey make his shocking confession later this month on Channel 5.
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