In November 1761, an attempt by MacNaghten and his followers to abduct Mary Ann from a carriage on a family journey to Dublin Parliament and elope with her failed, when he shot and mortally wounded her by mistake. He was taken to Lifford Courthouse in Donegal, where a court found MacNaghten guilty of murder and he was sentenced to execution by hanging.
In November 1761, a bid by MacNaghten and his companions to kidnap Mary Ann from a carriage on a family trip to Dublin Parliament and run off with her ended in failure when he accidentally shot and mortally wounded her. He was apprehended at Lifford Courthouse in Donegal, where a court determined that MacNaghten was guilty of murder and he received a death sentence by hanging.