Mathews and William Tryon, the governor of the Province of New York, were also accused of being involved, as was a member of Washington's Life Guard, Thomas Hickey, who would eventually be executed for his role.
On July 8, the New York Provincial Congress, after Mathews was found guilty of treason and subversion, was sentenced to death and was to be executed on August 25.
He was first sent to Hartford, Connecticut under the care of Abraham DePeyser, and then sent to Litchfield, Connecticut on July 21 and placed under house arrest in the home of Major Moses Seymour, whose orders were as follows: you are directed and required to take him under your Care and him safely convey from Hartford in Hartford county to Litchfield ___ aforesaid and him there hold and keep in safe Custody permitting him only to walk abroad for the Benefit of the Air in the Day Time and to attend Divine Service at some place of public worship and that under your law or that of some other trusty keeper on the Sabbath Day, until you secure further Orders from me or from the Provincial Convention of the State of New York.
[5]Mathews, in a letter to a college classmate written during his imprisonment, denied his involvement in the plot against Washington: I have made so many fruitless applications lately that I am almost discouraged putting pen to paper again.
[4][7] Mathews, in his claim for compensation to the Royal Commission in London for the forfeiture of his estate in the colonies, had it written that "He had formed a plan for the taking of Mr. Washington and his guard prisoners, which was not effected by an unforeseen discovery that was made.
[9] On November 27, Major Seymour placed the following notice in the Connecticut Journal seeking help in recapturing Matthews for the reward of $50 ($1,568.98 as of 2021).
The notice read as follows: On the night after the 20th instant escaped from Litchfield David Mathews Esq., late Mayor of the City of New York, who was some months since taken from hence, on being charged with high crimes against the American States, but on giving his parole was admitted to certain limits, which he has most basely and perfidiously deserted.
In 1778, a party of twenty men "with their faces blacked and otherwise disguised" led by Captain John Schenck went to Flatbush as part of the Whaleboat War in a failed attempt to capture Mathews.
[13] In August 1778 Mathews sustained injuries in assisting British troops and Manhattan residents in extinguishing a fire on what is now Front Street along the East River.
In June 1779 an attempt by Loyalists to kidnap New Jersey Governor William Livingston, a distant Schuyler cousin of Mathews, failed.
Thomas Jones described Mathews as "a person low in estimation as a lawyer, profligate, abandoned, and dissipated, indigent, extravagant, and voluptuous as himself.
[18] Failing to gain an appointment as that province's attorney general, he traveled to Cape Breton Island, which in 1786 was administered as a separate colony.
Although an elected house of assembly was to have been established, this did not occur, and Mathews became a leading and divisive figure in the small colony's politics.
Mathews' granddaughter married Vice Admiral James Noble, who served on HMS Agamemnon with Lord Nelson.
Catalina Mathews' descendants include solicitor and editor Horace Pym and British historian Keith Kissack and can be found in England, Canada, United States, Australia and New Zealand.
Also Lewis Wilkieson Johnstone (1862–1936), who was also a grandson of Edmund Murray Dodd, was a Conservative member of the House of Commons of Canada representing Cape Breton North—Victoria from 1925 to 1935.
[21] Fletcher was referred to in 1779 by Col. Isaac Nicholl, Sheriff to Governor George Clinton, as "an exceedingly bad man" who was "willing to do all the hurt he can" to the Patriot cause.