The web site of Brooklyn's Fort Greene Park claims that, after the Revolutionary War, "the British Commander in charge of the Prison Ships was brought up on war crimes charges and was subsequently hanged."
1. The British never prosecuted their personnel for the murderous neglect of American prisoners.*
2. Captain William Cunningham, Provost Marshal, oversaw a prison in New York City, not the prison ships off Brooklyn.
3. The British supposedly executed Cunningham after the war for forgery, not for the mistreatment of prisoners.
4. The report of Cunningham's execution was a fabrication, as was the "confession" that accompanied the report in several American newspapers.
*The British did court martial Captain Richard Lippincott, of the Board of Associated Loyalists, who reportedly took New Jersey militia captain Joshua Huddy from a prison in New York City and hanged him in New Jersey as an act of retaliation for a loyalist's death. The court martial acquitted Lippincott. This was for the murder of a prisoner, but not a prosecution or investigation of the systematic prisoner abuse that left thousands of Americans dead in the course of the Revolution.
For more information, please consult Forgotten Patriots: The Untold Story of American Prisoners During the Revolutionary War, by Edwin G. Burrows, and The Prisoner in the American Revolution, by Charles Henry Metzger, Society of Jesus (Jesuit).
Blogger J. L. Bell wrote of the apparent survival of Cunningham decades after the supposed 1791 execution.