In 1865, Stonestreet testified in the trial of the conspirators in the assassination of President Abraham Lincoln. He stated that he had known Mary Suratt, a parishioner of St. Aloysius Church, for more than 20 years and that while he had only infrequently seen her in the past 14 years, he had never known her to espouse treason. This testimony occurred against the backdrop of growing suspicion of Catholics, as several suspects proved to be Catholics; some who were suspicious of Catholics went so far as to accuse the Catholic Church of involvement in the assassination.