Man Pleads Guilty to Manslaughter in 23-Year-Old Cold Case in New Hampshire

• A New Hampshire man pleaded guilty to manslaughter in his father's beating death.
• The crime occurred 23 years ago when the perpetrator was 17 years old.
• The case was a cold case until recently.
• The incident took place in New Hampshire.
• The guilty plea was made by Douglas Herlihy for the murder of his father, Paul Herlihy.