A Grass Valley man remains in custody in county jail after allegedly hitting his partner and tying her up so she couldn’t leave their residence. The woman, who was not identified, sought treatment at Sierra Nevada Memorial Hospital Dec. 8 for the alleged assault, said Grass Valley Police Capt. Rex Marks. She told officers that Brandon Thomas Roberts, 28, hit her repeatedly with his closed fists the night before. Roberts also allegedly tied her up to prevent her from leaving, but she was able to get free that morning. A be-on-the-lookout advisory was issued, and Roberts was located at a …