As the dog started biting the sea lion, Kelly runs to the scene, but the sea lion was far from being saved as it was losing blood profusely.
It happened on Saturday, near Goff Cove Beach where Giffords, her husband and stepdaughter were staying.
Police said that Kelly and his 18-year-old daughter were walking on the beach when the dog saw the sea lion and broke away from his leash.
Nathan Straw saw the scene and quickly began filming it, later providing the video to the Times and other news stations.
Kelly was soon joined by two other women who wanted to help get the dog away from the seal. The video shows on woman holding the sea lion by the tail as she pulls it and tries to take it.
But they were unable to get the dog to stop biting the seal.
It wasn't until Kelly took the dog by the head and started vigorously shaking him that it finally let go. The seal limped into the water when it was released.
He then took the dog back to the beach while his stepdaughter cried.
"Mark Kelly came over and picked the dog up by the collar, shook it, called the dog out by name, and that's when the dog released. Mark Kelly was able to walk the dog back to the parking lot," Straw said.
Police were called around 2 p.m. and came to find the sea lion dead on the beach.
They said that the sea lion beached itself before it was attacked, indicating that it might have been sick.
"It was legal for her to have the dog on the beach this time of year, and she did have it leashed. It was so strong that it pulled free of her when it saw the [sea lion," Capt. Jason Kravetz said.
It would only have been illegal if the dog was encouraged to attack the animal, which did not seem to be the case.
Currently, the dog lives with the stepdaughter in Texas.