 While in prison, Long was mysteriously shot and killed by a guard, and Milam came to believe that the murder had been arranged by Trespalacios.This incident drove Milam and some of his friends to plot to kill Trespalacios, and when that plot was discovered, Milam was again imprisoned.Milam and his friends were sent to Mexico City, where they were held until the fall of 1822, when Joel R. Poinsett, U.S. Commissioner of Observation to Mexico, secured their freedom.