Jeffrey Geary, 30, faces numerous charges including attempted murder and armed robbery and is to remain in custody while the assessment is conducted.
Geary's lawyer says his client was exuding some bizarre behaviour at the time and ordered the test to determine whether or not he can be held criminally responsible.
Fas Gas clerk Jaysen Reyes suffered injuries to his face and hand during the Sept. 11 robbery.
Eric Ayotte, 29, is also charged and is to appear in Red Deer court Thursday.
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