On Friday, RadarOnline.com posted a photo of Russian singer/pianist Oksana Grigorieva with her front teeth chipped — an injury the 40-year-old claims was the result of a punch she received from actor ex Mel Gibson during a Jan. 6 dispute.

According to Radar, the photograph is part of the Los Angeles County Sheriff’s Department’s ongoing domestic violence investigation, which could result in battery charges for the Braveheart actor. The former couple are embroiled in a custody battle over their eight-month-old daughter Lucia.

As investigators prepare for a possible interview with Oksana’s 13-year-old son — a potential witness to that assault — another witness has stepped forward with photographed evidence of Oksana’s injuries: her dentist, Dr. Ross Shelton.

TMZ writes: “Dr. Shelden says he has known Oksana for 12 years. According to the declaration, Oksana came in the day after the incident and told him Mel had hit her, but she was not more specific. The doctor says in his declaration he saw evidence of “blunt force trauma” as well as physical damage. Something significant — in the declaration, Dr. Shelden says Oksana’s teeth were not damaged … just her veneers. He says one veneer was knocked completely out and the other was broken in half…The doctor wanted to take pictures of Oksana’s mouth, but not to create a record for authorities — he wanted them for his lab for the purpose of repairing the damage.The doctor says Oksana did not want the pictures taken, and had expressly said she wanted to protect Mel. But Dr. Shelden persisted and got the photos, although he says Oksana was so reluctant she would not look into the camera.”

Dr. Shelton was reportedly so concerned about Oksana’s well-being that he offered to allow her and her children to stay in his home.