A dog was shot in the head and wounded by a Brinks security guard last week, and the dog's owner now is looking for justice.

The guard said the 119-pound bull mastiff was lunging at him. The dog's owner, Eric Wafer, said his dog, Betty, just wanted to be petted.

Part of the incident was captured on surveillance video, and San Francisco police are investigating the shooting.

While bull mastiffs generally can be intimidating, Wafer said Betty is not.

Wafer said he took Betty for a walk last Friday morning in the city’s Hunter’s Point neighborhood, and Betty somehow got out of her leash. Shortly after, he heard gunfire. Betty had been shot in the face.

"I went running after her, and by the time I turned the corner, I hear a bang and yelp," Wafer said. "There’s two security guards sitting there looking guilty as heck."

NBC Bay Area obtained surveillance video from a nearby camera, and although the video is grainy, the guard can be seen walking backwards and Betty can be seen walking toward the guard and then past him when she was shot.

The police report says the dog lunged at the guard, but the video doesn’t show that.

Wafer said he asked the guard if he shot the dog, and the guard admitted to it.

"He came up with a story about him attacking his partner," Wafer said.

The next step is for the police department to turn the case over to Animal Control, which had not happened yet as of Monday night.

Brinks corporate did not respond to requests for comment.