My dad got roofied at Rudyard’s bar

Over the weekend my parents went to Rudyards bar located in the montrose area on Waugh Dr. While my mom was waiting for my dad to get himself a drink she was approached by a man as she described as White male between 50 and 55 years old. Solid white hair. Full head of hair. Solid white beard and mustache. Blue eyes and smooth cheeks. After she took a sip of her drink he told her “looks like you’ll be stuck with me tonight” which prompted her to call my dad and asked him to hurry back. Once she called the man left and they thought it was over but before leaving my dad drank my mom’s drink because she didn’t feel like drinking after the incident. Once they got in the car is when he became limp, irritable and couldn’t form a proper sentence. He was immobilized. They came back home and he sleep in the living room floor passed out(he had 3 drinks and he is not a small guy). In the morning he had no recollection of anything within that time. This morning he took a drug a test and it was positive for buprenorphin a date rape drug. If anyone has experienced this please let someone know. This is a neighborhood pub so he may frequent this location.