A private eye says he was running on pure instinct when he helped apprehend a teen accused of stabbing a shop worker over Pokémon cards in a hobby store in Auckland's Newmarket. 

A Hamilton 16-year-old will appear in Youth Court.

Thomas James says such incidents and lower level crimes are fairly common in the area. 

He says it was a dangerous situation. 

"He made a decision when he left the house that morning, or wherever he left, to carry a knife on him. You only carry a knife if you're prepared to use it."

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