Conrad Hilton's father was called to assist police when he was arrested on Monday (22.06.15).

The 21-year-old socialite was taken into police custody for entering ex-girlfriend Hunter Salomon's Hollywood residence, and he was reportedly in such ''bad shape'', Rick Hilton had to enter the building to help calm his son down.

Once inside the property, Rick persuaded Conrad to stop shouting while officers got him on the ground and handcuffed him.

According to TMZ, only Hunter's mother, actress E.G. Daily, was at home during the time of the incident, but Conrad followed her around, calling out for his former girlfriend.

Despite Hunter reportedly taking out a restraining order against the hotel heir - whose older sister Paris Hilton infamously starred in a sex tape with Hunter's father Rick Salomon - he won't be charged with violating it as the LA City Attorney has no proof it was served.

However, Conrad has been charged with trespassing, which could see him jailed for six months if convicted.

Conrad's latest arrest came just a week after he was sentenced to a $5,000 fine, 750 hours of community service and to undergo treatment at a mental health and substance abuse centre following an incident on board a British Airway flight from London to Los Angeles last July.

The hotel heir had previously pleaded guilty to a misdemeanor count of simple assault following his 10-hour meltdown on the plane, during which he reportedly screamed threats at flight attendants.