They had fled across the border to Bangladesh amid heavy fighting between the Myanmar military and rebel insurgents in Rakhine
Omar bin Golam Rabbi was arrested with 22-year-old brother Hasib bin Golam Rabbi over the killings of their parents, who had emigrated from Bangladesh three decades ago.
Hasib, who had confessed to killing his father, but not his mother, according to police, will be tried now only in the case. He had earlier said that Omar was innocent.
Omar had told investigators that his brother killed both parents.
Police had recovered the bodies of Golam Rabbi, 59, and Shamima Rabbi, 57, on Apr 24 from their San Jose home, and later arrested their two sons.