Oliver Prinz von Anhalt – Zsa Zsa's adopted son with ninth husband Frederic Prinz von Anhalt – died on Christmas Day after being hit by a car the previous Sunday.
According to TMZ, Oliver had been knocked unconscious and remained in a coma until Sunday 25th December, never regaining consciousness.
It's not known whether he'd heard the tragic news about his mum, but in a strange twist, his father had known nothing about the accident.
The news site claims self-styled royalty Frederic had no idea his son was even injured, let alone fatally, until the coroner called him on Boxing Day night.
Instead, he thought his adopted son was in Germany, Frederic told TMZ.
Oliver's brother Prinz Marcus von Anhalt paid tribute to Oliver, writing: "RIP Prince Oliver Leopold von Anhalt (my Brother)
Rest In Peace? Nein!! Live the Afterlife in the fullest, like you did before."