Cops say Aaron Hernandez's brother, Dennis "D.J." Hernandez, experienced a bipolar episode less than three weeks before his ESPN arrest ... one that resulted in a wild police chase through Connecticut roadways.
It all allegedly went down on March 8 -- just 15 days before he was accused of hurling a brick at ESPN's headquarters in Bristol -- when cops say they attempted to stop D.J. in his silver Hyundai as he was driving through Cheshire.
According to the Cheshire Police Department, D.J. was driving erratically and at high rates of speed -- at one point traveling through grass fields in front of the Cheshire Correctional Institution.