Before 1913 Texans suspected of being insane were charged and tried in criminal courts. After weighing evidence and arguments presented by the state and the defendant, juries would render a verdict of insane or not insane. In 1913 the handling of insanity cases was reformed by the Texas Legislature. The new system provided for hearings to be held before insanity commissions in civil proceedings. Query whether J. P. Leeper would have fared as well before a commission.
A reason for his erratic behavior could have been that his wife was deathly ill in Missouri at the time. The Richmond (MO) Democrat reported that she was buried on May 23. That means she probably died on May 21, give or take a day; therefore, she died a week after her husband was declared sane (technically, not insane) in Sherman. Was he distraught over the state of her health? Or was she perfectly healthy until she died of fright after learning he had been set loose?

J.P. Leeper moved to Birmingham, Alabama where he operated a sash, door and blinds business at 2201 Morris Avenue, while boarding at the Palace Royal.  (1889 Birmingham City Directory).  
He died January 15, 1889 from abscess of the liver at the age of 51 in Birmingham, Alabama.  His body was taken to Richmond, Ray County, Missouri for interment in the city cemetery.  He had been a lumber merchant in that city during the 1870s.

His will was probated in Jefferson County, Alabama during the February 1889 term of the Probate Court.