It ties the Molly Maguire background to another event of that period : the death of James Carey , the informer on the Irish National Invincibles who committed the Phoenix Park murders of Lord Frederick Cavendish and Thomas Burke .
It ties the Molly Maguire background to another sensation of that period . 
 This was the death of James Carey , the informer on the Irish National Invincibles who committed the Phoenix Park murders of Lord Frederick Cavendish and Thomas Burke .