Thomas Markle Jr – whose half-sister Meghan has been dating the young Prince for several months – was arrested late on Thursday at the home he shares with his girlfriend of two months, Darlene Blount, in Grants Pass, Oregon.
The 50-year-old, whose father Thomas Markle Sr is also Meghan’s dad, was taken into custody after the row which is said to have escalated into violence.
An official police log of the incident, which spelled Meghan’s brother’s name incorrectly, stated: ‘Markel and Blount got into an argument.
‘In his drunken state Markel grabbed a gun and pressed it to Blount’s head in an attempt to get her to leave.’
It added that Blount rang the police after locking herself in the bathroom for safety.
Markle was charged with menacing, pointing a firearm at another person, and unlawful use of a weapon, according to police records.
Deputy Jill Elardi, of Josephine County Sheriff’s Office, confirmed the arrest and charges.
She said: ‘He was arrested at 11pm on January 12 and released on Friday at 10am. He will be going to court for it.’